Quote:
:b5: I don't think I'm supposed to play this if white doesn't ni-ren sei. Maybe e4 or d15 is more conventional; I don't know.
Well, when white plays the shimari pointing towards your chinese formation, it limits black's potential on the bottom and at high levels arguable makes the game more favourable for white. At your level, you don't need to worry about it too much. You can always choose to approach the lower left instead, though.

You can consider playing high instead of low (K16) since it is better at forming a moyo.
Quote:
:w8: I see that white is protecting his corners a bit while I'm kind of backing off. Maybe playing that way isn't such a great idea if it allows me to kind of expand a bit too fast. Sure, I can be invaded, but at what cost? A few points in the corner? Because of that, I think that approaching at H9 with

is an idea. Maybe not a good idea, but an idea.
The move you played seems fine. Both K17 and R9 are low, so black doesn't have as great potential for a board-spanning moyo.
Quote:
:b13: Protect my corner, get a few points to the side. I hope I protected it correctly; my instinct was on R16 for

Kicking at

is the right move. It doesn't really protect the corner, though. Instead, it makes white's group heavier. It's only right because of the R9 stone, which cramps white's extension later. For

, this is a bit loose, and you can play one point higher at O16 to leave a lot less aji for white to exploit.
As mentioned, technically white can still invade the 3-3 point after that, but until white's group starting at R14 is safe, invading there will hurt the first group, so you can attack R14 and then descend to S15 once white's group has become safer to solidify the corner.
Quote:
:b15: I start "protecting" cuts this way throughout the game. R16 was also another choice I would've played before, but I'm trying this for now until someone can tell me about it.
Sometimes this is good, sometimes it's not. In this case, I like connecting solidly because it gives white less forcing moves to try and do something to the corner later, and makes the corner almost certain territory.
Quote:
:b17: Makes it so white can't invade ever. I think. At least that's what an 8k told me before, but I think H3 was played at K4 or somewhere closer during his review there.
This needs to be P10, or maybe P11 if you're feeling aggressive. White's group isn't alive yet, so the more pressure you put on him while staying solid, the more free moves you get as white wastes moves to save his group. Regarding 'makeing it so white can't invade ever,' it's quite possible that the surrounding situation was different, as an invasion seems quite possible to me here, though perhaps unwise at the moment. Also, an 8k player, while certainly having a fair amount of knowledge to impart, is really not an authority you should trust completely on whether something is invadable or not. I am significantly stronger than 8k, and you shouldn't fully trust my judgment on such things either.

The cap at

seems fine, and you should be thanking white for making you play

, but here, black has lots of potential on the bottom, so walling it off is very good. Black has much less potential on the left, so walling it off is not so good. You can just play N8 and ask white how he's going to win when he's given you a quarter of the board without taking much for himself.
[quote:b25: I'm panicking; I don't know what to do to limit its spread, so I'll just allow myself to be split. I think that's only a "good" idea if I have really close backup.[/quote]
In this case, being cut is fine, because both sides have support, and white's stones are running on dame, which is to say that at the end of the game, they're not going to be enclosing any territory, but are on spaces that would have ended up worthless. You could just extend solidly with

but your variation turns out well also.

Let's not hane everything.
Quote:
:b39: White's possibly not out just yet if it he ignores L11. Playing at M13 here was just me admitting that I couldn't contain him and trying to contain the spread from this direction.
This explanation contains a fundamental misunderstanding, I think. You don't need to kill white. In fact, you shouldn't even try too hard, because it can leave you with terrible weaknesses if white lives. All you need to do is to keep playing moves that keep the pressure on and give you an advantage, like territory or a solid influential group, while white wastes his moves saving his group. To that effect, you can play something farther out, like K13 or K12. In more advanced games, you will see black tenuki the local situation to play forcing moves on the opposite side of the board, because they're painful for white to ignore and when white responds, black has more stones available to eventually drive white into.
Quote:
:b45: I don't know exactly why I did this. I assumed he would play R10, but did he even have to do that? It gives him an empty table and some more points, sure, but my next move at

was something I was going to do anyways. Did it serve any purpose besides gaining me like 2 more points since he had to fill in one of his potential territory spaces?

is a thank you move that costs you points. It makes white more solid and it removes the option for bigger moves. If you must play locally, R10 is the move to play. It threatens to capture S10 or continue to Q10.
Quote:
:b49: Here I'm commenting about the fact that I'm unsure of my current development. I'll take the star point, even though it's on the 4th line, to try and secure some points in the lower right.
It feels a bit submissive, but the bottom right is so big, and I don't think you can swallow white's stone.

seems like a good reducing move for white.

I think you can safely play M7.
Quote:
:b57: I think attaching under is a way to make a base and link myself up.
White's stones are floaty and have no base. Cut at K5 or so and let white flail around and die inside your moyo. Worst case scenario, you give up the 4 stones above white's three and secure the rest as solid territory.

Instead of spending a move here, capturing M4 protects against this. In addition, it's not that dangerous for black even if white cuts without

. Black can connect at L3 and capture white before he can capture black.
Quote:
:b71: Extra precations that, once again, gives Sente to white. (I think I used that correctly.)
This doesn't protect anything that needs protecting. In effect, you took gote twice to protect something white couldn't cut. Much better to just jump in on the left and make sure white is left short of points.
Quote:
:b77: Here I am scared of cuts again.
This was necessary because of

. Better to leave

unplayed and strengthen this group instead.
Quote:
:b79: All right, let's invade! I still have room for a two space extension here and I can run out towards the centre if white does something else but block me from doing that. I'm right on white's sector line and I don't think I can get a concrete base in there, but I feel I have to do it.
This move seems fine, but make sure that white can't cut off your weak center group.
I'm not going to go over the rest of the game, because once black's center group is safe, white's short on points and the game is basically over.