Sitting in online cash games

[Hawt]

I remember TP said to never sit with more than 5% of your roll at a time. But I was also wondering, when you sit at a cash game online, do you always buy in for the max at the table?

For example, the 1/2NL cash games have a max buy in of $200 (100 BB's) and a Minimum of $40 (20 BB's). So obviously buying in for $40 would leave you at a disadavantage but what about $100ish?

Also for Limit gaves you sort of track your progress by saying you want to win "2 big bets an hour" but what about No Limit? At a 1/2limit game the big bet is like $2(right? .50sb, $1bb, and then $2 bb?) so if you were trying to make 2 big bets an hour, it would be like making $4 an hour. Can I just convert this over to No Limit and hope to make $4 an hour, or since it is No Limit should I bump it up a little bit since the pots are likely to be bigger?

Looking back at my big bet post, I noticed someone said that 1BB per 100 hands or something like that. And BrianSwa said that he goes for one buy in an hourish. Is that a good goal to set before sitting down?

Do you guys think that it is better to play limit online when you are a beginner and trying to build your roll? Because it seems like you buy in for less at limit games (online it looked to be about $75 for 1/2 limit, compared to 200 max for NL) and like 5% of my roll is $8...

Note: I do not have the intention of moving directly into the 1/2 cash games with my small bankroll. The math was just easier for me with those numbers.

Edit: Also, when looking for a cash game to join, what stats do you look for? (On Stars) how many people? what Players/Flop %, hands per hour, average pot?