I have been using Hostgator.com for about a year now, and I think they're great... never had a problem with them, and in my experience, customer service has been great.
I do not think that buying a domain name for 1 or 10 years would help you in the search engines. I do know that Google likes domain names that are a little older... so maybe after a few years, Google will add value to your site ranking because it's been around for some time.
But Google's criteria change all the time. I wouldn't worry about the changes, though, because they tend to improve in the favor of better websites... for example, it would be able to distinguish (if they don't already) between a domain name that has been parked for 10 years versus a 10 year old site that continues to get updated with fresh content.
It sounds like you plan on doing quite a bit of work on your website... I hope you are not overwhelmed... enjoy it!
