What i understand from ur thread is u r using 0awg power cable from battery to distro and from there 4awg to both amps. Is that so ?
Regarding fuses u have to understand few things. Fuse r a physical resistance for the current means too many fuses will ultimately affect sound quality. So, use the fuse which is absolute necessity, that's it. Another thing is fuse at amp is to protect the amp while fuse elsewhere is to protect the particular wire. Now coming to ur queries
Firstly, Distro fuses are for ur 4awg wires. 60A is too small. Use 100A for each 4awg. Dont count them in ur total Amp calculation.
Secondly, A 150A near battery will be sufficient. U can even try 100A, if it doesn't blow at high volume then should be ok. I am using 3amps and a processor, my 150A fuse never blew.
I have no idea about where and how to get and install the alt since i've never done it. Other gurus here can guide u better.
Hope this helps 