With reference to your Items 1, 2, and 3 here's my take:
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
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.