Dish also supposedly has a single wire multi-switch that they employ in some installations that require only one coax run to each sat box... however, in my experience not everyone gets one of these, so it's pretty hard to predict before you schedule your install.
To be safe, your plan of having extra coax and CAT5 seems like the right call. On that topic though, don't you want to run CAT6 as opposed to CAT5? GigE ethernet can't hurt if you're ever going to be networking computers over this connection and CAT6 doesn't cost a lot more than 5.
Back to the sat box question, most new boxes now should all have HDMI, so I think you'd be fine with that assumption.
Jason
