What kind of lighting to buy when there is no previous installed to use as a reference?
You should be able to install any off the (local) shelf armature, connect the wires and mount it to the wall/ceiling.

If you want power efficiency then you should prefer LED lighting which are currently some of the more efficient lighting solutions. 

One of the factors to take into account is how much light it needs to emit and where it needs to go. A single 100W incandescent bulb in a large hall is not going to cut it.

If you are wondering which bulbs to put into existing armatures then it's very likely a standard connector. For mains that is an edison base or bayonet mount in the UK.