Easy easy.
First is it production server or test one.
Which asterisk you have. If lower than 1.4.28 then you should use sail 2.4 if higher than use sail 2.5
sail 3 is quite fresh so it is not recommended for peoduction enviroment. Please read carefully instalation notes on sarkpbx.com/twiki
which kernel you have? Do you install proper dahdi with kmdls??
Pci cards can be added any time you want but I will kindly ask you read manual. It very well described howto do this and how to do that. There is no sense to copy manual from Jeff to forum. So please do it. There are no stupid questions so don't hasite to ask but try use manual couse there is risk that you can get RTFM answer