Adelie steered you right.
1. Buying a boat that isn't a lemon. What should I look out for?
Sound
hull, decent engine, good sail condition and
rigging, good evidence of previous owner just generally caring about the boat. Tons of good info out there on how the
survey a boat. You should have no issues hitting the ground running coming from the aviation mx world.
2. Big dog living with me on a small boat. New potty training? Astroturf? Any success here?
I lived with a 75lb Laika dog onboard my 27' for five years and cruised the
east coast during that time. Manageable and it worked, but I never did get him trained to potty on astroturf. You may have better success. I tried to limit my
passage lengths to under 36 hours, which is manageable at least on the
east coast. Left him with the parents when we left for the islands. One of the hardest things I ever had to do, but both dog and owner were happier than if he had gone. YMMV.
3. Learning to sail properly. (Anyone know how to use a sextant? I never want to 100% rely on technology)
Still working on that one myself. Until then I'm content to rely on a
GPS and 2 backups. If you're looking to sail far, paper
charts can get really expensive. You may eventually find it financially expedient to buy a
chartplotter and just have some small and medium scale charts for general areas. Or
trade with cruisers along the way.
4. Work and money in different countries. (I'm an aircraft mechanic But am flexible)
Tough one unless you have the ability to work remotely, or are willing to do menial jobs within the US. Outside the US opens a whole different can of potential worms. I've done an IT job since moving aboard and has worked well for me. Project-based work that has finite completion dates and don't require being on-call or on standby if something comes up is ideal. Schedules don't work well out cruising, and land-based employers have different expectations than what the reality often is out cruising.
5. Size of boat for safe world sailing.
Lots of opinions on that one! I like Adelie's broad range given. If you know the boat and have given yourself enough time to make the dumbass
mistakes before getting too far afield you'll be fine.
Good luck! It's an absolutely wonderful way to live.