I am new to flyer talk and I have never purchased a rtw ticket. I have read alot of information on the subject and I have some questions. My planned routing is as follows:

AMM-LHR (RJ)
LHR-HKG (CX/BA/QF)
HKG-CMB (CX)
CMB-KTM (CX and KA via HKG)
KTM-YYZ (KA and CX via HKG)
YYZ-BZE (AA)
BZE-YYZ (AA)
YYZ-UVF (AA)
UVF-LGW (BA)
LGW-TUN (BA)
TUN-AMM (RJ)

Is this doable?
I am a little confused about stopover rules, am I allowed to stopover in HKG when travelling from CMB-KTM. I don't think I am.
I would like to add Guam, but I'm not how this would be possible. I know I'd have to pay for one extra Asia segment.
I need to fine tune this itinerary. Any suggestions will be appreciated.
Thanks.