LOL...My apologizes in advance. Being new to my AS project and only having basic Mechanic's knowledge = my limited info

I will endeavor learn about this boat bow to stern. I really do appreciate your assistance.
This boat was purchased with no information so Im starting from scratch. I'll take a few pics of the engine and post which may help identify the details of the engine.
Yes, the tranny fluid appears dark brown, possibly burnt and not viscous when rubbed between fingers. I'll change the oil for sure as but it's sounding like a tranny rebuild my be in order. Any idea of a cost to do this?
The Tranny slipping is odd and occurs at about 4k RPM and 45MPh. At the same time RPM gauges start fluctuating on the dial. The bow of boat seems to start to slightly "bounce" and does not fully plane out. Most likely the Tranny slipping. Also The tranny does jump into forward a bit clunky and find neutral is a tad sensitive.
Sorry, my "would not fire" comment was not clear. The starter just clicks and has to be tapped with a wrench to get it to engage. From my experience that's from a flat spot in the starter windings.
The hard to start comment my be just getting familiar to the choke, throttle position, not flooding it etc. I'll mention it to the mechanic when I bring it in for the tune up.
Following your suggestion the boat will go in for a full tube up next week.
Mechanical details that I'm aware of from previous owner:
Engine was rebuilt a year ago and has approx 60 hours on it.
All boat wiring and gauges, dash removed and replaced with new.
Main prop shaft bearing / seal replaced
Newer Holly 4 barrel carb
Thanks again for your comments