a few elec. q's..

[giant killer]

first off.. i have been having serious problem getting my car started after putting the motor back in.. so today i started checking "everything".. well first thing i check are the fuses.. the 75 amp alternator fuse was blown.. could this affect say.. the brake lights?
is this a common problem and if so is there a common fix?
is this a dealer only fuse or should i be able to pick one up at napa?

second.. i relocated my battery to the trunk.. i am running a large 1/0 gauge wire from the back to the front.. i am wanting to redo how i have it setup.. would 4 gauge be big enough for the battery positive cable running rear to front?

thanks in advance... bennyb