Your first few attempts will be pretty poor - don't worry.
We can't help with positioning, as you've not said what the band consists of. Are we talking an all acoustic band, or electronic instruments and worse still a PA?
If it's a hybrid with some things amplified other things natural, then your only hope is to find a place where the balance is perfect - and if something is too loud or quite, move it in or out. Getting an amplified vocal to site nicely is hell! A pair of closed back headphones will let you move the zoom around to find this magical position! If your editor can handle higher sample rates and bit depths - just choose the highest setting that the zoom and the editor can handle. You can reduce resolution in the editor, you can't add back in what wasn't recorded!
Recording level isn't an issue - the red lights flash at you when it gets loud - so simply get the band to give you their loudest bit of the set - and set something that doesn't hit the tops of the meters. The display on zooms tends to fall off quite quickly - so quiet bits often look too quiet, but if you make sure you don't peak at the top end, you will be fine. I'd try NOT to use the limiter if you can. This takes experimentation - so just have a go.
