I don't know if you can do this, your questions lead me to think you probably shouldn't do it yourself. If you do go the DIY route read up on wiring so you know how to safely make the connections, properly secure the wires, how to run the wires into the box, grounding and all the rest. At 40 years I'd expect drywall or possibly plaster board and plaster. Which isn't much harder than drywall to work with.
Here is a decent article on getting started when doing electrical. Read up on it before you tackle this as a project. It isn't rocket surgery but you can get killed or burn your house down if you do it wrong. http://www.hometime.com/Howto/projec...ric/elec_1.htm
For light fixtures consider using these. http://www.homedepot.com/p/Halo-5-in...0WHR/204732243
You won't need a can, and it will give you the same look. They can be installed with just a regular ceiling box.