Im no expert but if it helps i will give you what I would do, and to be honest the most important thing i have is a laptop(the only thing i care about these days.).

1.BIOS: P-ATA + SATA
2.Make as little changes as possible and note all the previous possitions to return them to 'default' in case you mess up.
3.Probably not.
4.Depends what you want to do with it.
hope this helps.

and for people I dont like (and vice versa):
although opinions differ, please dont yell, im (really) only 13.