I guess
you might want to scour the web for forums and recipies dealing with this, it's not a bad idea, and in fact, many traditional restaurants will serve liquer based coffee drinks, but of course they have the licence to cover the lounge and the selection is rather sparce.
I know what you are thinking, and it's not a bad idea, you are basically wanting to open a bar with more of a coffee flavor to it, which in turn should bring in the coffee crowd as opposed to the bar flies which normally establish similar establishments. I like the upscale type of mentality with an operation like that and it's going to draw in a very pleasent target market.
As for the business plan, the primary purpose of it is to get what you have in your head as an idea and make it a working plan. Take everything one step at a time, you likely will have to address each issue out of place based upon any generic business plan format, but that's part of getting your own ship afloat. This is a site I reccomend for people that are writing their first one:
http://www.bplans.com they even have a free generic plan for people that want to start a kiosk, so it's right up your alley.
Anyway, good idea, go whith an upscale/traditional theme and don't be afraid to do even more then just coffee drinks, just keep your vision in tact and don't be tempted by the quick buck, if you do it right, you'll own a very lucrative operation.