I have previously done a complete rewire of my Yalta . Using tinned copper cable is a must . I used insulated twin core cable with an outer sheath for better abrasion protection plus looks neater .
I found it was cheaper to buy a reel of cable that was closest to the length of all the circuits I wanted to run . I got mine from KT Cables
http://www.ktcables.com.au/ . They have expanded now so not sure if they still have a retail counter at the new address but they do online .
You sound like you are onto it but a couple of tips anyway. It sounds like you will have individual dash switches for each electrical service which I reckon is good . I ran the positive thru a heavy fuse holder and also a compact isolator switch under the dash before the bus bar ..This was so all electric accessories could be quickly isolated with one switch . I have a negative bus bar as well . All my electronics are positive switched so the power is only fed to the dash switches until they are switched on then it goes to each unit . I have seen some installations that were negative switched where power was running around the boat to all units waiting for the earth to be completed by the dash switches . Not something I would do especially if its on an alloy . Have fun but you will be surprised at how much spaghetti you will end up with under there .
Cheers Chris