Point 1 - If you have a child to support I would have thought you'd have less money than the other members. Kids are the ultimate money pit. The rest, I assume, are DINKYs (Double Income No Kids) which would lead me to think they may have more disposable income than you rather than less. I agree with other posters that band related expenses should be split equally
Point 2 - The others are clearly people who need regular ego massage. One way of doing this is to go on to each other about how great they while another is to denigrate somebody else. Is that what you think they're doing? People often don't realise how they can hurt others. They probably do it partly because they don't realise it pisses you off and partly because they can. Try pulling one of them up next time you're feeling sh*te and see what the reaction is.
Point 3 - I can't add much more to what Lozz has posted. A band is made up of different personalities and I think it's that diversity that can make for a fine live experience. Were Queen crap live because John Deacon didn't headbang his way through the set?
I guess you have to decide whether you think you can negotiate these problems through (or if it's even worth trying) or not. Personally, If I'm in a band playing originals, I'm doing it for fun. Once that stops, I'm out.