Definitely start low with the xanax, despite you usually being able to take 2-3mg comfortably - 1mg sounds sensible, or even 0.5mg to start with. You can always add more but you can't take away..
Hydromorphone bioavailability is definitely higher snorted than taken orally - approaching double, not quite triple though I'd say..
(Oral: 30–35%, Intranasal: 52–58% according to
this)
I wouldn't throw alcohol into the mix if I were you (I know you're not suggesting it addyman but just wanted to make that point!)