Welcome and to answer some questions
Yes click on the edit button when you select expert mode and there should be an option which says extended HUD info.
3. I think this has already been asked (but with no soloution) but is it possible to play in 'expert' mode but with the guages turned on?
There is ESC and it drops you to the menu but thats not what you need it for you want to make screenies I think =) : Update just checked for key bindings and pause is bound to ESC so thats a no then
4. Is there a 'basic pause' button which doesn't drop you back to the options menu?