I agree with Pete. Spend more on sound than lights. Ideally, you're gonna want a couple of wireless lav mics and a good shotgun mic and omni mic. That'll be fine.
And yeah, with lights, depends on what you want and what the place is like. I always think it's really tricky to light interiors well. In my experience, unless someone really knows how to light well, the more lights there are, the worse it looks (comes off as phony and/or harsh). The interiors that I've shot that I thought really looked the best was just one or two simple soft, warm-colored lights coming from a direction that makes sense for the actual location of the set, and the actual lights on the set from lamps or whatever the restaurant has will usually give you a good amount of dimension to the image (a little bit of light hitting the tops and sides of the actors heads) that will also look natural. So you're really just using the couple of soft lights to add more light to the overall shot and quietly fill in spots here and there. But simple is the way to go. More than a couple of subtle lights and you increase your chances of it looking bad, and it also takes too much time and saps everyone's energy. Light quick, light easy. Every opportunity you have to not use lights at all, take it. It might involve shifting the actors to where the light is better, but it's worth it. That's just my opinion, of course.
I think that video cameras these days can capture images really, really well, in the way that our eyes see it. I see film students blasting 1000 watt lights at their actors like they're shooting on film, but they're not, so it simply looks harsh. As long as you're paying attention to the exposure and getting that right, then I think most of the time, if something looks good to the eye, you can get it to look good in the shot without a bunch of fuss. Though, it depends on the style. This works best for a naturalistic style. If you're going for something more stylized, you just have to experiment beforehand until you hit upon what you want.
Something that I wish someone would have told me: take an extra minute right before you shoot the shot to make sure that it's the best that you can make it at that point in time. I'm generally happy with the films that I've made, but since I don't use much in the way of lighting and I like to shoot fast, I miss some details that I would have caught if I had just taken a couple of seconds to think about it before we rolled. That little tweak to a light or getting something out of the shot really makes a difference between something looking all right and something looking great.
Anyway, the thing with sound is that it has to be captured as well as possible, because you don't really have any leeway with bad sound. It's not as much of a subjective thing--it's either captured well or it's not, and you can't do much with it in post if it wasn't recorded well. Two lav mics and a boom mic is the standard and generally best way to go.
I've probably said too much. I hope something in the ramble was useful. Best of luck!
