We've been asked for money too and though its something we didn't do I have no problem in sticking £30 in an envelope for them. We had a list and some people didn't like that (we had it for relatives who wanted to club together to a 'set' of something) and we didn't mind if they gave us a gift that wasn't on the list, or gave us cash, or gave nothing at all.
We live 300 miles from our friends and its costing us a lot to go to their wedding, considering its in school holidays in a holiday area, we're taking our annual holiday at that point now, something we wouldn't usually do, just so we can be there for their day, so £30 imo is a perfectly acceptable amount of cash to give.... knowing my friend, she'd be happy just to see us whether we could give cash or not.
Yes you can wear white, but I'd avoid a white maxi dress with a veil. White with polka dots sounds lovely to me, and I was Bridezilla!!!! Unless of course, she'll be wearing a white polka dot dress.
YABU, or rather, you're projecting YOUR standards onto her wedding, and YOUR standards onto your DH. That's NU! But it doesn't make you right. If you want a new dress, tell your DH to give half of what he wants to (considering they're marrying abroad, your finanacial situation etc) and if he can afford the other half to buy you a dress you'll be happy to wear.
Lots of people wore white to my wedding and didn't look like the bride, and with hindsight I could have looked a complete mess, all eyes would have been on me anyway because that's what people DO at weddings (unless laughing at the person who is clearly trying to upstage the bride and only succeeding for the wrong reasons).
Sorry for the long post, but although I wouldn't ask for money, with the amount of weddings I've been to this year I'm starting to think its the least wasteful option and not as rude as my social conditioning seemed to think.
Have a lovely day.