coating is not an antifoulant.. the bottom paint
goes on top of that so whether a hull has been coated is immaterial to the use/frequency of antifouling paint
. It's a preventative measure for osmotic blisters on the hull. 2 years between major haulouts is doable esp if you can keep up inbetween with scrubs and cleans.
Avoid ferro boats.. steel boats can be OK but again you need to be very careful that they've been properly built and maintained. (one old Folkes 37 in our marina was being scrubbed after sitting as a liveaboard for years, she had 3" of mussels everywhere. Luckily a travel lift was close by because at one point the diver scraped off a patch and opened up a thumb sized hole in the steel - can you say 'glug glug'?)
Good steel boats come at a premium, not a bargain, with additional upkeep and watchfulness required. Aluminum is similar but with different issues, and wood boats are another thing altogether. In your situation a well found fiberglass boat will be the best choice.
Your need to liveaboard in Vancouver complicates things a lot. The co-op route is probably the best one. Heather has limited space, as does Pier 32. Fishermans Floats no longer sanctions new liveaboards.
As expensive as the cost of living in Vancouver is, living aboard (legally and conveniently) is not 'cheap' either.