1. How many years experience of poker do you have (or probably better, rough number of hands under your belt), before you are able to consistently win and this type of challenge is possible?
I was a losing player for quite a while. I started off playing 200NL in the local casino like 6 years ago. I probably lost $10,000 over the course of about 18 months before I started winning on a consistent basis. It took me a little while to adjust to online, but once I started taking it seriously, it wasn't too bad.
2. As a noob, what would be a realistic challenge to set myself? I currently have a $25 bank roll, and am playing all sorts of games, but always micro limit (and quite a few freerolls as I desperately need the practice).
I'd say set aside a budget, not a bankroll. Figure out how much you're willing to lose each month, and use that money to play as much as you can. Your primary goal should be to play as many hands while losing as little as possible. And definitely take advantage of the forum freerolls and money added buy-in games. I'd also suggest picking a specific game and stick with it for a while. I'd suggest SnG's since they are very easy to master and it doesn't take much to be a decent winner at the micro levels