I get the impression that the processing time varies depending on where you're applying - you might like to look at the website of the Visa Section in the country concerned - you can find it on
www.fco.gov.uk - there's a drop-down menu in the top left corner: go for "UK Embassies Overseas"
As to the amount of money you need, I think they deliberately don't publicise this, but the answer really boils down to "enough". If your fiancé's salary is above the minimum wage, and other married couples are able to live on that salary without having to fall back on benefits, then that should be sufficient. I think the length of your engagement would also have a bearing on it, given you won't be able to work until after you're married. They may also be concerned as to whether there's a reasonable prospect of your finding employment once the marriage has taken place and you're legally able to work.
Someone else, with personal experience, might be able to express this better than I....
