GET IT!! trust me you won't regret it. as soon as you get your 3.55 I would recommend installing rebug 4.65 and when it comes to the bigger HDD you can load games from USB just fine.

plus you can use PSNpatch to get online with your backups without issue

 

The instructions for CFW installation is mostly the same for any model.
Some precautions are: turn off Automatic Updating, turn off your Wifi if you must, remove your Game Disc (They have a Ps3_Update folder burned onto them), and finally you should format the USB you use to decrease chances of data corruption when transferring it in Recovery Mode.

If you're really cautious about it, go REBUG 3.55.2 first then use a hombrew called Toggle QA, this will insure a lower chance of bricking when you update to the newer firmware.
You could also as the person you're buying from to update to CFW for you. What you want is REBUG 4.65.2. Also tell them to dehash it (They'll know what this means since they downgraded the console, using Toggle QA is essentially dehashing if you want to do it yourself.)

There are pkgs of game updates so you don't need to go on PSN for them, you DL from PC instead. It's faster than direct PS3 update and you keep the update on your PC if you need a backup.

 

There tutorials in the Tutorials and FAQs section. Some of the outdated stuff is still applicable like Cyan's Multiman guide.

I don't want to be a self-advertiser but...
There's my guide which assumes you're a complete noob that did like 1 hour of research, although it is long as hell because I cover all the general stuff.

I made it last summer so it doesn't cover "ODE," the alternative to CFW that only plays backups and nothing else (No homebrew or free PSN games).