Newbie needs help...

Hi!
I've already read many threads and tutorials about cfw on ps3, but I still got a few questions about cfw...
It is a PS3 Slim (CECH-2004A) with 3.50 (original) installed.

- update to 3.55 ofw
- bigger hard drive installation (?)
- install rebug 4.82.2 via safe booting mode

Is that correct so far?

My questions about that:

- should I install a bigger internal hdd or using an external hdd would be better?
I've seen a thread where there are problems with metal gear solid 4 (act 4) when...

Newbie needs help...