Never fly a mainland Chinese carrier when you can get some excellent fares on Asiana, Korean or EVA! Saigon has excellent hotels for pennies - forget the big chains! If you really want something nice I like Ma Maison Boutique Hotel, but there are many many others. Put down the address of your hotel - no, no need to book first (actually the address is of little importance). I would suggest buying an open jaw ticket (into SGN and out of either DAD or HAN). 2 weeks will go by in a flash - limit your stops since transport in VN is very slow (best to use domestic air - Vietjet or Vietnam Air).
Please do a little
research - rather important here.