Answers to your questions,,,
1) yes that crappy laser will fit on the gun......it is 20 bucks down the toilet.
I had one for a .22 just to see how a 20 buck laser worked. It couldnt handle the recoil fro a .22. If you put it on, and never shoot it, and just show it to people who don't know anything about guns, it will be great.
2) Handle covers Hogue grip sleeves:
They may not say they are for the P95 but they will fit.
3)All mags are different. some hold 15. It is difficult to say with out looking at the mags. If you can only get 12 in .....it is a 12 round mag.
Go shoot ot learn about it , clean it often and you will have a very reliable handgun that really should last a very long time.