Upgrading swapping canabilizing on the iPod 80gb 5th gen.

I noticed that user Joseph Blewitt mentioned on 6/13/15 that he used a laptop hard drive to swap in to his ipod 80gb .

Is this really possible? Everything I have read so far makes it sound like you must use exact apple certified hard drives. ( i have not read much as this is my first contact with apple harware, so cut me some slack)

So here is my situation and question(s)

I have an ipod 80gb 5th gen. (SN: last three = YMV) that i purchased off ebay.

When it arrived it was (and still is) working, but the back cover was actually falling off (how lucky can a newbie get eh?) So i figure this is a perfect time to refurbish and upgrade, so what i would like to know is;

1. Can I use any 80Gb ZIF Hard drive ior must i use an apple hard drive?

2. Does the stock 80Gb logic board support the 120gb hard drive? -- iow,can i put a 120gb drive into this unit with the existing logic board.

3. The button in the center of my logic wheel sits crooked and stays indented; is there a fix for this? Will i need a new center button?

Thnx for any help / advice

James