use the lowest octane you can use w/o "pinging" etc... ive never used anything but the lowest in all my bikes and ive NEVER had a problem. do a search and youll get lots of stuff to read.
as for the choke, i turn it on the whole way to start it and shut it down a bit after starting to the desired RPM. if its hot out then you wont need it for long if at all. if its cold out then you will need it for a few minutes to help warm up.