I never net a fish I am going to release.  Down here in WA it is illegal to take them out of the water.
I would get a hand operated bilge pump & make sure you have an electric one as well.
Research proper electrical bonding on an AL hulled boat.  Stray electric currents can repel fish & cause excessive corrosion.
Down rigger ball eight sorta depends on how deep & fast you fish, diameter/strength of cable, & the type of gear you fish with (Flashers add more drag, plugs need to be fished faster.  If you use the manual DR's, I'd put on 150LB braid & see if 10lb does the job.  If you use a light ball but put out more cable to get deep, you will have more line from your reel out & if it is mono (i fish with braid) the extra slack in the line will result in more lost fish right after hook-up.
I'd see how the Suzuki trolls before mounting/rigging a kicker.  FYI there is an optional troll system for this motor that allows you to adjust RPM in 50 RPM increments.
Electric Downriggers used to be illegal unless you had a MD's note.  They are nice, but if you always have 3+ people, 1 to fight the fish, 1 to crank down riggers, & 1 to handle the boat.  The gear cranker can net the fish.
Just as in TV's, larger screens are mo better; especially if you have GPS & Sonar going.  The new CHIRP sounders are a game changer.  It's the first sounder in over 30 years of fishing that i have confidence will detect Salmon reliably.  If you troll around for 30 minutes, see/catch nothing, & the tide is in the correct phase,  it's time to move.  I like fishing, but the wife likes to eat fish.