That is a long time LOL. How much will that run you about? You must have a great forum to register for that long haha
I did mine for 5 years I thought it would help with pagerank, but doesn't seem to have. But I don't wory about PR much anymore.
As far as I'm aware the age of the domain helps with pagerank, but how long it has been registered for in advance doesn't. I also think pagerank is becoming less and less relevant with search engine results these days.
I always go 1 year. Am just too cheap to do anything else. lol And I always go with godaddy. I didn't realize that there were cheaper places to go, but then again I haven't really looked.
Most of the time I renew for 1 - 2 years, rarely will I renew for 3 or more years. Having your domains renew at the same time can get a little pricy. I have about 10 domain names, at $9 each, I would have to shell out an extra $90 - $100 dollars at one time.
I almost always just renew for a year at a time. You gain nothing by renewing longer (SEO wise) other then you don't have to worry about missing a renewal, which I get emails alerting me when they get within 3 months of renewal.
It depends, my gaming guild site is renewed for 3 years each time it comes up since I know it isn't going away, other sites mostly yearly.
I know the feeling back about three months ago I had 45 of my domain names expire... I only renewed like 20 of them and I still had to shell out close to $250 ... bad timing on my part.