Make sure to read everything in the Beginner's Digest first, then go to the subforum of the game you choose to play and read everything in the digest there.

Make sure you adhere to proper Bankroll Management. Due to variance, you need to have enough money in your account to continue playing at the stakes your at when your bad swing comes (and it will come!!!). When you first deposited your $50 you said you played 25nl. That's absurd. You only had 2 buyins for 25nl. You didn't have enough of a roll to comfortably play 5nl let alone 25nl. Bankroll management really can't be stressed enough. Even the best players go on bad run in which they have to rely on their deep roll to keep them going. Also remember bankroll management doesn't just tell you when to move up, but also when you need to move back down.

As for the multi-tabling, it takes time to develop. Have you tried both the tile and cascade format?? You may find one easier than the other. And you shouldn't go from playing 1 to jumping up to 6 or so. Just add another table and play 2. Then when that gets easier add another and play 3 etc. Keep doing that and you'll find you can play more comfortably. Which will increase your hands per hour and if your a winner, it will speed things up.

As far, as book suggestions, here are a few that I've been recommended. Theory of Poker, No Limit Hold'Em Theory and Practice, Ace on the River, Harrington on Cash. I've read through most of Theory of Poker and NLHET&P and they are both solid reads. And if you are playing MTTs or SNGs then you will probably want to pick up Harrington on Hold'em Volume I and II. I've read one and he gives alot of examples and help you work through why he is making the play he does.

As far as the hand goes, I personaly would toss it to his continuation bet because your call preflop is merely for set value and since you didn't hit you should just toss it. I think that there may be an argument for flat calling his flop bet (floating) and assuming he gives up on the turn you can take it down (or you have the better hand). I really don't like raising because there are few better hands that you make fold. Calling would at least keep the pot small, which since your hand is marginal at best you want to do.

I'm assuming because he showed you the bluff that is why you are showing this. If he hadn't you would have chalked it up to being beat and moved on. Keep your head up and play smart and you'll be back to 200nl (correctly) sooner than you think.