We have concrete slab in basement bathroom where we are going to tile the floor. Just removed the styrofoam wrapper around the toilet pipe which has been cut level to the concrete floor. Because of the wrapper, there is a gap between the outside of the pipe and the concrete going around the pipe which is the thickness of the wrapper, about 1/2" or so, and the gap is about 1" deep. Does this situation imply the use of a twist-type flange? And does that mean we should tile up to the flange? Or tile first (not covering the gap), then install the flange?

As do-it-yourselfers on most of the basement finishing project, this site has been INVALUABLE! Thanks a million...

The "wrapper" was put around the pipe to create a gap between the pipe and the concrete. A toilet flange will fit inside a 4" pipe and outside a 3" pipe. If you have a 3" pipe and the "warper" had not been used you would have to chip out enough concrete around the pipe to install the flange.
You can tile up to the edge of the concrete and then install the flange. You do not have to be all that precise. Just have enough tile under the flange to support it. Or you can place a couple of dry tiles next to the pipe to determine proper height and install the flange. Then when you do the tiling you can slip tiles under the edge of the flange.

Probably best for you to tile first. Then coat the flange and the pipe with liquid soap. The soap will make removing the flange easier. Put the flange in place and mark where to drill the holes for the screws anchoring the flange to the floor. Remove the flange and drill hole for screw anchors. Get a drill bit for drilling glass from Home Depot or Lowe's. They don't last long but they are cheap. Use the glass bit break the glaze and start the hole in the tile. Then switch to a masonry drill bit and hopefully a hammer drill. Use the masonry bit to drill through the tile and into the concrete. Set the anchors. Prime and glue the flange and set it aligning the screw holes with the anchors.

When you put the flange in place to mark the holes, don't forget to make sure that the slots for the toilet hold down bolts are in the correct place. They should be the same distance from the rear wall. Otherwise you toilet won't sit square to the wall.

Thanks a million! We tiled first. Now for the doors...

What about the doors?