Re: Lack of Confidence
That is a good list. Personally, I'd fix the cockpit drains first since that can be a 'boat sinks' kind of problem.
The electrical is really a can of worms and can be difficult to really fix, and certainly to do properly. Corrosion and iffy connections can really make things hard to track down. Lots of time with a voltmeter and ohmmeter. A knowledgeable DIYer can do it certainly, but if you aren't confident that is one that might be worth paying someone to look at.
The diesel and trans service you can probably do yourself.