deore 10 speed cassette, 11-34
I’d go for a 11-36 if I were you, you’ll want that extra bit of range.
then settled on a 32 or 34 chainring but will a 9 speed chain ring work or do I need a 10 speed chainring?
I’m running a 35-tooth ring, and find it hard to keep the front down in steep stuff. I’d probably go with the 32 unless you ride with a load of 2*9 running speed demons like me.
Do you hit your chainrings on things? If so, yes. If not, no.
Do I need a chain device? IF so what are the recommendations?
I’ve been running fine with an old front mech with carefully done limiter screws. Once my bash arrives from Wiggle though I have one of the Hope chain guides to go on. Can’t report back on how good they are yet, but certainly looks well made and weights sod-all.
Crank bolts, do i need shorter ones or spacers?
Ones for two rings if you’re running a bash, otherwise short ones for a single ring.