Rinda makes the scanner but have not seen where they have it for the MEFI 7
I don't even know what a 7 is, wonder if they took a 4 and have had have upgraded it 3 times over the years
Only down size I can see is if you need help, your probably stuck with going back to them for help. Don't know of anyone that has the knowledge of a MEFI-7 if there are issues. Make sure to get all the manuals
The trim cylinders have been replaced, or the boat use to have a MR and the drive was replaced with the MC-1
What trim tab?
The ventilation plate looks to have the front part of it broken
Welcome
Have a look in the link and explains most. If you still have questions post a pic so we can help
https://forums.iboats.com/threads/miscellaneous-mercruiser-information.323278/
The first patch most likely didn't hold because the prep was not clean. Can also happen if resin or MEKp is old.
Need to get all thecompramized glass out, even if it goes clear thru the hull. Once all ready then layers of mat and resin will fix it. If using epoxy note the amount of time...
That's the cool fuel module
Its a drain plug (item 7) which is used to drain system for winterization. Merc does not sell plug seperately. I would remove it and see if you can find something like to replace with.
https://www.mercruiserparts.com/bam/subassembly/31757/15045/60
This is a Merc but your connector will look similar. Connector has a cap cover on it in pic that is removed to use. It ight be near the front of motor around thermostat
Have you check the throttle linkage?
Remove throttle cable, with TB fully closed see if it just slides back on. If it does remove and adjust one more turn so it apples a slight pressure to help hold it closed
Gas should be clear, yours looks yellow.
Does it smell like gas?
As Scott said there is a lot of crud in the filter
It could be the old gas was just in the filter and not in the tank. If you dump the filter again and it still looks the same yellow then maybe it's lost. Don't know your call
Use vise grips or small pipe wrench on fuel line to remove. Hole other nut with another wrench. Replace line with new brake line. Fittings will be the same
Looks as fuel has gone bad, so it needs to be pumped out and disposed