Small Stakes No-Limit Hold'em

Hello all. First post. I started playing poker seriously in March of this year. Mostly online MTT and SnG's. ROI around 24%, ITM around 15%. I have done pretty well for a newbie I guess, meaning I'm not in the negative currently :) and have built the bankroll to around $400. (won two $4 buy in - 180 man SnG's, and got 1 second to help bump it up from $50)

I have recently (past few days) tried out some NL cash games to give it a shot, and my game seems to fit pretty nicely for it, maybe better than tourney play. I've had winning sessions the past few days at 9-handed .50/$1 and .25/.50 tables.  I won or broke even most sessions so far (without any experience or knowledge of NL cash games) but I'm realizing I should probably drop down to lower stakes with only $400, and study up before I get in trouble even though I've been running good. What level should I drop to? I feel pretty comfortable and strong beating .25/.50…but should I still drop down lower?

Also, with my new interest in NL cash games, I recently purchased Professional NL Hold'em. I am liking it very much so far, (I'm only 50 pages in). Great job guys! Should I wait to fully digest PNLH a few times before checking out Ed's new E-book? Big difference between 6 handed and full table in these games?  

I feel my game is decent for a newbie, but I have ALOT to learn, and still consider myself a student more than a real player. I needed some help with the cash game stats/tracking. Can someone explain the "3/ 100 BB" type of stats exactly? As well as the amount of buy ins I should have? (I am BRAND NEW to cash play) Also, is there a site to look up your opponent's cash game stats? (I found plenty for tourney stats, but not cash play, I'm guessing there is not) Also, a site/program to keep my own stats? Before you answer, keep in mind I am not a huge math guy (working on it) so simple is best for me at this point.

Sorry for all of the questions, and for writing a novel. I have just been thrust into NL cash games, and I've been really enjoying the play as opposed to tourneys. (this all is supposed to be fun right!?) Thank you in advance for your advice, and thanks to Ed, Matt and Sunny for your books!

Thanks for the info, I have a pretty good grasp of bankroll management for tournament play, but the volatility associated with cash games makes bankroll managment much more crucial.

Do you know of any programs/sites to help you accurately calculate your BB's/100 hand?  Thanks again!

Thanks Nemo. I appreciate the info.