Woah, this thread actually managed to span 4 pages.
The answer to simplicity's question is actually quite ironic. There's no need to think about where to go, what to do, how much to spend, etc. Spend whatever you feel comfortable with. If you're going out to play, don't ruin the experience by trying to innumerate everything. Go with the flow. :P
You might even enjoy yourself more if you didn't know where you were going, or what you were going to be doing. Take it as an adventure! You definitely don't sound like you've got somewhere to be, or have someone to report to, so just relax and enjoy.
I miss getting lost when I first got here so much...
As for where/how to get laid, the answer to that is that it's actually far more difficult not getting laid.
G'luck!