I have been involved with cinema exhibition for the last decade and a half or so. I can tell you that you will almost certainly not make money playing first-run films ina 50-seat single-screen venue, regardless of the kinds of concessions you are selling.
First, to book a first-run picture, you will potentially need to compete with other theatres in your area ("clearance issues")--for obvious reasons, distributors will not give the same title to two nearby theatres. You will have to check with the distributors about this. If you have no other first-run venues within, say, 5-10 miles, this might be a nonissue, in which case you would be able to potentially book whatever you want.
Second, when booking first-run titles, you need to commit to the distributor that you will show the picture, exclusively, on a screen (your only screen) for a specified period of time, typically at least two weeks, and often three. Most titles will be played-out after the first week and a half, which is why so few single-screen theatres are playing first-run. You will also need to commit to paying a minimum guarantee versus a per centage of the boxoffice gross (typically 50% or more over the course of the film's run--you pay either the guarantee or the per centage, whichever is higher). The guarantee would likely be a limiting factor for a venue with so few seats, so you would probably be losing money on every title that you play.
You also have other expenses that need to be paid, regardless of whether anyone shows up to buy tickets: rent, insurance, depreciation, staff, booker, film/hard disk shipping, maintenance, cleaning, etc. This will eat you alive in a single-screen theatre with 50-odd seats.
My experience in the industry is with 35mm (still an option), but digital projection doesn't change the economics in any sort of fundamental way (it actually makes them worse, due to the more expensive equipment and maintenance and faster depreciation).
In short, you really want to have at least 2-3 screens with at least 100-200 seats if you are playing first-run, even in a small town/open zone. You need to be able to always have a picture that people want to see, and a 3-week-old title won't be it (in most cases), and you need to be able to meet guarantees. Also, most people don't want to see movies in a 50-seat venue...that's a screening room, not a movie theatre. You need to be able to provide them with a reasonably large screen (say, 20-30' wide, at minimum) and an awesome "big room" sound system, which you can't do in a screening-room-size venue. Finally, with a dinner theatre especially, you need to justify the cost of the kitchen staff, and spread out their workload. A single-screen venue gives you the worst possible situation here.
A better option for what you are considering would be to try a cinema/drafthouse type of venue (playing older titles, possilbly art-house titles, without minimum run guarantees and typically at 35% flat). That way, you could play a double-feature each night (probably separate admission, though), charge less, and make more money. Art-house films also typically have longer shelf lives than mainstream hits, and play better late in their run.
Regardless of any of this, film exhibition is not a great business model in most cases. You could probably generate better grosses per square foot with just about any sort of retail. The only reason to do it in your case would be to get people into the building to show them whatever else you have to offer.
Finally, there is no way that you will be playing mainstream first-run anything on any type of projection system other than 35mm or DCI-compliant. The distributors are (wrongly, IMHO) super-paranoid over piracy and would never think of sending out unencrypted copies of their percious material.