Anchors in a solid plaster wall

My vote is for option 3. I've never seen angled pipe flanges either, but you could make a couple for this purpose out of 1-ft lengths of pressure-treated 2x6 with a pipe-sized 45-degree hole drilled in each. Then anchor those to the walls vertically. That would give you the added advantage of spreading your anchors out a bit in the cinderblock, rather than having 3 or 4 smallish anchors on a 2" radius or whatever.

I don't like option 1 just because you probably don't accurately know the strength of the concrete ceiling either locally or across its span, and that option's failure mode could be disastrous. Not to mention the likelihood (as you mentioned) of hitting steel and needing to rent a core drill and use it upside down on the ceiling. Not fun at all.

My main concern with option 2 is the tension load the bracket anchors are going to see. These blocks are very strong in compression (and by extension any anchors used in them are strong in shear), but not strong at all in tension (and by extension anchors don't resist pullout forces).

A screw directly in plaster or drywall is not very strong. Over time it will work its way out and leave a hole in the wall.

It's OK to use a nail to hang a framed painting or photograph. If you do this, first put a piece of scotch tape on the wall, to resist cracking. Make sure the nail is angled 45 deg from vertical. You can pull the nail out when you're done and it will only leave a small hole that is easy to patch. (Many people don't patch, but you'll still see the hole when you repaint.) There's a limit to how much weight I'd want to put on nails in drywall, though - if it tears out, it's a mess.

There are a variety of drywall anchors that you can use for larger loads (see http://www.naturalhandyman.com/iip/inffastener/infanchor/infanchor.html for a good list). Most require you to drill a hole first. Be careful when you do this, because if there is wiring or plumbing behind the wall you could make a lot of trouble. Threaded anchors don't require drilling and are very easy to use.

For the most strength, screw in to a stud. I do this with towel bars especially, because I know people like to use them as hand-holds. Also, people yank towels from their holders, which puts a lot of strain on the wall.