I'm starting a website and I'm planning to purchase the domain off GoDaddy.
It asks me how long I want to purchase the site for. I can pick 1 year, 2 year and 5 year etc.
At this point in time, I'm not sure how successful the site will be - it may be that it's not successful at all and I may abandon it. I'm thinking of just picking 1-2 years.
However, if it is successful, what's stopping GoDaddy from charging whatever they want for the renewal? Are there any rules governing how much they can charge to renew my site? Is it possible that once I've purchased with GoDaddy to renew my site with another registar?
I'm not actually too sure what GoDaddy does to be honest. Do they own all the non-registered sites on the Internet?
Renewal by definition is the same price or the normal price if the first was at a discount. Read the terms of services and contract !
In an even that you don't like their renewal's price you can have your domain transferred to another registrar.
For SEO the longer is the better, so I'd advise 5 years.
Nobody own non registered domains, of course.
Protip: never let your web host be the registrar
In short for what GoDaddy (& others registrars) does: No one owns a domain name. Nor the registered, nor the not registered. All the domain names are only "rented". GoDaddy is in charge of the technical part and administration (registration, administration, payments & co.)
Concerning the choice of the duration: