Theres a bit of a knack to starting them but if it's warm it should start without the choke, you need to get a feel for where the pistons are (by gently prodding the kickstart) before you kick it.
If it's set up well it'll tick over around 1000 rpm and mine will pull off around 1500rpm no problems but it's a '28 and that's after a bit of experimentation with the jetting and some nervous plug chops, most others I've seen/tried are not that good, a good few revs tend to be required. It shouldn't just stall when sat there though.
Spark plugs? People tend to change them when it doesn't like starting/ticking over.
If it's totally standard whatever is "regular" in Japan will be fine, it's what it was designed to run on.
Really you need to find out what (if anything) has been changed and if it's not completely standard in every way check the jetting, higher octane fuels or just avoiding running flat out in top in the first place are both just bad ways of making up for poor or (even worse) unknown setups.
That said though I'll probably run 97ron on the track next week
_________________
Please do not PM me technical questions, if you can't find it on the Forum start a thread