I think Boaty is on the "a lilo is good enough" end of the spectrum - but that puts him in a minority, at least on having a fair to middling chance of arriving! and I have a sneaky suspicion that last night when posting
he was going a bit shoreside stir crazy and that alcohol may have been involved.........bluntness used for clarity!
But FWIW, I think 40 foot not a bad ballpark to aim for - not strictly necessary and length alone won't make any boat seagod proof, but on average 35 foot plus gonna make life easier (which is a safety
item), at least than sub 30 (including a lilo!). But design also rolls into that.
wise, 4 not a bad number. Can of course do with less - but it all rolls into making life easier (aka more pleasant). Of course also have downsides with more folk onboard - even a 40 foot plus boat is a smaller space than most people are used to for extended periods and especially sharing it with others! One of those things yer never know for sure until you do it - my perfect crewmate might be "your" living nightmare! (and vice verce!).
Me never gone transat, but you sound like you are in the ballpark to give it a go - at least if a chunk of those miles have been as Skipper
(always a bit! different from being crew - some folks good with "the buck stops here", others not so.....middle of an ocean when the poop starts is not the best place to discover which! or to learn).
Anyway, welcome to CF.