1) your procedure is right. But dont forget to do the firmware updates via Recovery mode, just to be "more" safe. But one thing I'm curious about is, what you said: "(as Install Package files has been removed)"! when did that happen? Is it on Rogero's 4.21/4.30 CFW V2.0? because i am on Rogero 4.30 CFW v1.0 and there is an "Install package files" icon. Maybe I missed a couple of update news, anyways as I said your process is right. I did it the same way, but I was on a 3.55 CFW first and also I skipped the qa flag part.
2) sorry I cant tell u that because I have only used geohot's first CFW, kmeaw and now rogero. The name rebug (re-BUG) sounds...
3) obviously 4.30 is better because it can play games signed with up to 4.30 keys with out a fix .
4) sorry about that too, I dont use PSN. My country havent got one (took me ages to realize that)
5) i dont think thats possible neither safe. What i would do is take out the drive and install it on a PC and install windows on it (let it format it). Then plug it back to the other ps3 and let it format it again. Consumes times but I THINK its safer.
Just take your time and google a bit till u think u are full.
PS3 Slim 120GB
Rogero 4.30 CFW CEX
1TB TOSHIBA HDD
Playing: Shift 2: Unleashed, FIFA 14 and GTA V
Wish to get: Beyond: Two Souls, Need For Speed: Rivals
Can't wait for: Watch_Dogs and DRIVECLUB