Using anything "high-end" for the mains cable is a total waste of
money. Whenever I need to replace one, I use one with a molded mains
plug from a store that sells such things, ~2-3 euros per piece. You'll
never hear any difference (and neither will anybody else) and I don't
think there's much difference to see either - I hide mains cables the
best I can...
For the signal cable, I don't believe much in that
hoo-hah, but anyway it makes no sense to install something clearly inferior if you're going to replace it anyway. Unless you are going to install an all original cable, it's of course up to you what kind
of connectors you want to use. I'd use whatever fits your amp/receiver
directly, if you plan on keeping the deck yourself.
Remember that you need to run the extra ground wire from the chassis, if you end up using RCA connectors. In DIN cables/connectors, it is connected to the sleeve.