if the targeted keywords include numbers, then go for it, if not try to use another word for those letters cheers !
Depends on the niche. Having a number in the domain may help it to stand out and attract more eyeballs in the SERPS.
It won't impact your rankings, but people may be less likely to click the link. Why not conduct some keyword research and find a variation of the domain name, then see if it's available?
numbers are good if they make sense.. 4 and 2 are the overused numbers i guess? SEO doesnt have a problem with numbers
That will not be an issue with SEO, However, if you can include your main keyword on the URL, that will be ok.