Someone did the calculations a while back. If you do it on a regular PC, the amount of time and cost of electricity makes it not worth it. I'm not sure how true it is, but it sounded about right. You may be happier mining litecoins. Litecoin - "Silver to Bitcoin's gold" Bitcoin Alternatives
Bitcoins aren't deep web. They are used in the deep web but there are many legal uses for them. There are a few websites that accept them for completely legal objects, like clothes, electronic, and even stuffed animals. Either way I've never seen the rule saying you can't discuss the deep web. This is the only one that comes close: http://forum.grasscity.com/matt-mernagh-chronicle/400369-grasscity-community-forum-rules.html
I wish I did. Honestly I wish I had spent like $100 even on bitcoins when I first learned of them. They were about $7/BC now they're at like $43? That's in like 6 months or so; shit's crazy.
Not worth it. People with over 60k in investments (100+ high end graphics cards) only pull in like 2k a month. Not to mention, Nvidia cards are completely useless for mining, and even if I could i wouldn't put the extra stress on my rig for a few extra bucks.