[Old Guy with 87 GT]

i'm not an expert but i am pretty knowlegable ,i'll try to help

#1 shouldn't hurt the alpine ,the alpine should have it,s own fuse built in (in back of it).....your main power lead should be high enough to carry the currunt of both amps

#2 your remote wire should be able to power several amps ,all it does is kick a relay in the amps for the main power lead .....it's ok to split it

#3 that actually sounds like you have a short somwhere ,double check all your wiring before upgrading fuse......actually triple check everything ......if it is shorted or wired wrong it'll do damage to somthing ,if it hasn't allready
,just turning the amp on shouldn't be blowing the fuse unless the valume of the stereo is turned up (both amps sitting idle -no valume -shouldn't be drawling more then 30 amps)......the noise you hear is usually an indication of somthing shorted or not wired right........if you can't find any problems ,try a 40 amp fuse first ...if it blows with the valume all the way down then it means somthings wrong

#4 every thing looks right in your diagram ,i did notice you have all the speaker grounds marked with a ground ........is that for a chassis ground or for connecting with the components marked ground wires .........some components can be wired with the speakers grounded to the chassis but most of your higher end amps and stereos can't and doing so will damage them ......if your amp or stereo provide a ground for speakers then thats the way it needs to be wired

well hope i helped .....good luck with it