Your boyfirend can renew his passport before the expiry date. The maximum the passport office can add to the new passport for any unexpired time on his currrent one is 9 months - ie he would get a new passport valid for 10 years & 9 months. It is a good idea to renew your passport a while before you need it to travel as it costs a lot more to speed it through. It is also a good time of year to renew it now. The nearer it gets to summer the busier they get.
Heres the link to the passport website
http://www.ips.gov.uk/passport/apply-renewing- when.asp
What do you want to know about visa requirements? If you are perfectly ordinary people and not terrorists or serious criminals for example you just fill in the visa waiver form that you will be given on the flight over to the US. You only have to apply for a visa in certain circumstances. Here is the visa information page from the US Embassy
http://www.usembassy.org.uk/cons_new/visa/inde x.html
If you need to apply, please do so in plenty of time because it takes months to get one.