I suggest that you look at reselling first. Managing servers is not something you can pick up over night. That said, more specifically to your questions:
1. How would I start up?
As mentioned, start with a reseller plan. The benefits are that you do not have to worry about managing the servers as that's taken care of. You can also start off with lower costs (and thus lower risk). Lastly you can use the chance to really test out whether this is something you like to do (no sleep, high stress, extremely competitive market)
2. Where do I get bandwidth from?
As long as you are reselling, or even getting dedicated servers, you do not have to worry about this. They all come with bandwidth. Just make sure that it's multi-homed and not that the capacity isn't maxed
3. How much does bandwidth cost.?
If you are reselling, a GB can cost 1-1.50/GB. If you are getting a dedicated server, you may be able to get 400GB for 99 (this is however not the norm). If you want to colocate, it can range from 100-300 /mbit (300GB thereabouts)
4. How much does it cost for an OC3 line?
You are probably far from getting your on for quite some time.
5. Where are the best servers?
There's a few. But more importantly, ask yourself what are the service attributes you want to uphold, and correspondingly your budget. For example, Rackspace, Servint and more can be considered as extremely reliable. However they cost a lot more.
6 Is it easy to learn linux?
Good server administration? As easy as learning anything new from scratch (i.e not easy)