Fish finder will largely depend on where you fish. I fish a small, narrow and shallow river so down/side imaging and fancy fish finders would be nice, but for me not really necessary. I have a Lowrance X4 and it works perfect for what I need if for which is depth, water temperature and bottom structure/composition.
I have an old hand me down bow mount trolling motor. So, no advice there.
For seats and mounts I went with 3 Cabelas high back angler seat. They work great and have held up fine. I'm 6'8" and 270#'s, so I put a lot of stress/torque on my seats. Only complaint I have is the buttons for the seat back hold down straps broke pretty easily. My buddy has a "button repair kit" and after about 30 seconds they were fixed. I think you can get these kits at any craft/fabric store for a few bucks.
For seat mounts I highly reccommend Springfields scratch and dent site. I bought 2 pin mount bases, 2 - 13" pedestals and an adjustable pedestal for my captains seat. I saved a significant amount of $ by getting all of that stuff scratch and dent. And the scratch and dent was at worse barely noticeable and some looked completely brand new.
https://www.springfieldmarinescratchanddent.com/
This is from my build thread. The pedestal I got retails for $200. I got it scratch and dent for $75!!!
Here is the manual adjustable (11-1/4" - 15-1/2") pedestal I'll be using for the captains seat.
Here is what made it "scratch and dent". I probably would have done just as much damage installing a new one.
Only other damage I could find on it.
Here is the pin mount bases. They look in perfect condition to me. Can't find anything on them that makes them "scratch and dent". They'll be getting painted to match the boat regardless. I'm using the standard base for the rear bench/deck and the offset base for the bow deck. Figuring the offset base will alow more leg room when fishing from the front deck.