if i colo with a datacenter, do i need my own router, do i have access to my server anytime i want and is my only duty is to keep my server healthy and colo provider keep their network running or am i also responsible for the network as well?

i've never colo before, just want to know what is my duty when i colo.

btw, what kind of question should i ask/know when contact a colo provider. i wish there is a faq on colo.