Can I do a "press 1 for sales" "press 2 for t

Can I route an 800 number to my asterisk box if I have a T-1 with VoIP?

Can I do a “press 1 for sales” “press 2 for tech support” with asterisk?

Will it put people on hold if all lines are busy?

Yes, all of these things are possible. I recommend you have a look at the links in my signature below.