My personal thoughts would be to cater first before you do a restaurant. The flavor profiles of any restaurant are a challenge and you have to serve to the masses and what they'll buy BUT you also want to be different.
For me, I'm not a fan of PS so I can't really tell you. Same issue with slaw. Both have so many varieties you could go nuts.
Make the que the best you can and go from that.
IF you seriously want to get into it, get an FE100, start catering small. You need to put more time into your BBQ flavors as that's what they'll be paying the most for. Sides will come.
Do a survey and start eating at all the Q within say 10 miles, what you competition will be and be VERY serious about rating them and getting comments. Take a few friends, take your wife.
What do they like, what don't they like.
For ME, sauce is the #1 thing to worry about. When I ask people about restaurants they like (people, not Q guru's) they always mention the sauce first.
then of course you have beans. In Texas it's pintos (but not for me, I like the navy style beans)
For the menu (we're in TEXAS Todd...)
Brisket of course,
Ribs (Spares or BB)??? think quantity and food costs)
Sausage (go with the Hill Country texas style sausage)
Butts should definitely be there, texas or not, there is so much to do with them)
Fries/Potatoes (do a stuffed baked potato for lunch/dinner)
Chicken (1/2's)?
Dessert? Market usually demands cobbler around there
You going to have to come up with something to get people in there and keep them in there and the time/effort/flavor of you Q may (or may not) do that. People are fickle.
Catering allows you to develop a following, control your costs and get it down before you open a restuarant. You won't have long from opening to do that, so do it before you open.
Want some free advice? take the time to read through this and other Q forum Pro sections. You're not the first and there are LOTS of free lessons, stories and much more information. Lots of good info out there.