With reference to your Items 1, 2, and 3 here's my take:
1.
Bilge pumps should be wired directly to the house
battery bank, with appropriate
fuses and switches (AUTO-OFF-MANUAL).
2. Your
VHF antenna atop the
mast should be OK for both 2 meters (144-148mHz) and
marine VHF (156mHz). To be sure, you need to insert an SWR meter in line. Mine actually has a lower SWR on 2m than on
marine VHF!
NB: it will NOT be suitable for UHF use.
3. The SSBs need to be wired directly to the house
batteries also. Use #6 wire, with 30-35A
fuses in both the positive and negative leads, located close to the
battery. The in-line fuses in the 718
power cord are OK to leave in place. Run the AWG6 wire as close to the rig as you can, to a small terminal strip. Using jumpers, you can use the terminal strip for both SSBs, the VHF, etc. Then, cut the
power cord from the radio(s) to an appropriate length, leaving the inline fuses near the radio(s), and attach these cords to the terminal strip.
If you follow this procedure, you'll be all set for the day when you replace the 718 or just wire in a marine
SSB to the (now) existing terminal strip.
Bill
WA6CCA