First congratulations!
Second..well finances hardly ever work out perfect with children...back up to the bare necessities, use all that time that you are not playing to enjoy the wife pregnant, and soon the kids...
Err one question on twins...why do you think you will have twins? sounds like you just took a test yesterday? a mite bit early to tell...though it is true older moms have twins more often, it isn't much more often than 'younger' moms I think it is like double..but double of 1 out of 100 is still pretty rare...
On sleep....do you currently have a problem with your 5 year old? or you mean dreading the whole first few years? if it is the first few years, then you might want twins, left together they tend to comfort each other and not need mom as much
...what I mean is look at the bright side