As far as the Boxster goes....

You can go to www.pelicanparts.com and see and/or ask about them on their forums.

I do know that even simple engine work must be done from below, so you will need a way to get under it. You might do a little research on blown head gaskets, too.

Early cars did not have door locks that you could unlock with a key (remote only) so if your car battery went dead you were locked out. Porsche came up with a retro-fit on this so if you are looking at an early car be sure to ask about this.