Welcome aboard. Interesting read on how you acquired your baby. Obviously she was meant to be yours. Congratulations.
To answer some of your questions:
Repower.... 4 stroke is the way to go if you can aford the initial cost. The savings on fuel will be almost twice what a 2 stroke will cost you IMHO. (The only exception might be the Evinrude e-tech which gets great mileage for a 2 stroke. (Talk to Bgreen about his)
Steering: Hydraulic is the way to go, but there's really nothing wrong with cable as long as you maintain it.
Radar Arch: Great if you have radar and GPS, otherwise why bother? I like the Atlantic Towers units for cost and functionality. Hard to beat the cost for a "Tower in a box" that they sell.
https://www.atlantictowers.com/
I'll leave the paint to the experts here. Why would you want a macerator pump in the fish box?
In all cases, once more, welcome. :)
__________________
1987 V20 w/1987 150HP Yamaha on a Shoreland'r Trailer
1978 16.5 Airslot w/1996 120HP Force on a Four Winns trailer
1996 V21 w/1993 200HP Mercury on a Shoreline Trailer
All towed by a 5.7L Hemi Durango.
If God didn't have a purpose for us we wouldn't be here, so
Live simply, Love generously, Care deeply, Speak kindly.
(Leave the rest to God)
Silence, in the face of evil, is itself evil. Not to speak is to speak, not to act is to act. God will not hold us guiltless.