help me pick some parts

[axela]

ok so i got my systema super max and i want to get some parts
but I'm not sure if they will fit
here is what i got so far

i want to know what ring will work better

http://www.wgcshop.com/pcart/shopper...WA002_srch_PTW

http://www.wgcshop.com/pcart/shopper...A007_cat_Sling Swivels


this part here i know it fits just want to know if it has the foam insert
and if its any good

http://www.wgcshop.com/pcart/shopper..._cat_Silencers


will i have to mod my gun to fit this ?
is it hard to install ?

http://www.wgcshop.com/pcart/shopper...RAS-14_cat_RIS and RAS



and this is for my KWA P226R
will this fit direct on or do i need to replace my barrel

http://www.wgcshop.com/pcart/shopper...26JS_srch_P226

and i need some mags there is 3 kinds and i dont know what one to get

http://www.wgcshop.com/pcart/shopper...6RT_srch_P226r

http://www.wgcshop.com/pcart/shopper...-FM_srch_P226r

http://www.wgcshop.com/pcart/shopper...6RJ_srch_P226r


Thanks for all the help