Well done on starting up! The first week is always the hardest and youll probably come up with a million things that you had never thought of, but rest assured - its the same for everyone!
The most important thing in a cafe environment is to buy a tamper that is ergonomic to use. A tamper with a poor handle can lead to RSI.
We have two favourite tampers, which we stock. The coffeelab design tamper has removable spacer rings to adjust the height of the handle so that it fits you hand comfortably, as well as rubber grips along the handle to cushion your palm. These design elements were part of the reason why the coffeelab tamper won the coffeegeek.com editors choice award, ahead of other tampers such as the custom-made Reg Barbers. In fact, Mark wrote that "[t]his is the BMW or perhaps more appropriate, the Maserati of the tamper world."
The Espro tamper is also engineered with ergonomics and durability in mind. It is particularly useful in a cafe where multiple people make coffee because it gives an indication of when a 30lb tamping pressure is reached, so it eliminates variation in tamping pressure as well as stopping baristi from getting overzealous and potentially hurting themselves over many coffees.
Two tamper options often come up for discussion; convex vs flat and custom-fitted vs standard size. I have done some tests using a bottomless portafilter and I have to say that I havent had any difficulty getting consistent picture perfect pours with any of the options. Convex is much more popular than flat in the commercial environment and on busy shifts it seems to make things a little easier, but thats just my gut instinct.
Hope that helps,