1. I disagree, I think your fuseki is fine relative to other things. If you don't have any time to study, don't bother memorizing joseki. I suspect that joseki is already leading you astray ( seems to be a misunderstanding of a basic joseki, for example). Just try to ask yourself what the purpose of each of your moves in the corner is, for now.

2. Just because invading is a good move doesn't mean you played a poor opening, and just because your invasion lives doesn't mean that your opponent played poorly. (Your opponent has already invaded twice by , btw!) For now, you should just play more games. These will improve your instincts for how and where to make your groups live easily, and how to harass enemy groups.

3. This is absolutely right. For now, take your time and, for every move, try to ask yourself what your options are, and what the advantages and disadvantages of each move are. Practice this as you play, and you'll get better. If you rush through, you'll never get to apply what you're learning. (Think of this as practice for Step 2! )

4. Keep playing games and doing tsumego. The more you do, the more obvious moves like C18 will be. If the byo-yomi setting you are using are preventing you from thinking ahead in the game, why not use longer settings?