I like to cut in cans with the suitably sized hole saw. Sometimes, you need to take a wet sponge, or even a putty knife, to knock down the higher points of the texture so that the can's trim will lay nice.
Like John says, it depends on the type of building and the fire rating of the overall building as to whether you'd use the firebox type cans or not. For one and two family dwellings, unless it's in a crowded downtown area with special fire codes, you'd almost never use them. For multifamily dwellings (apartment buildings and the like) along with commerical work that is of fire rated construction, then you'd use them. Certain cities with strict fire codes (like Ney York City and Chicago) feature almost everything you can think of with regard to fire resistance.Talking of recessed cans- do you have to fit fireproof enclosures over the can within the ceiling in the US?