[sirwired]

Well, if the popcorn itself is fine, you just need to paint it, not re-apply popcorn. If the popcorn is REALLY old, you must prime gently w/ oil-base primer first. Either way, just about any mid-grade flat in "stock" white for the topcoat will do. You can either go with a decent contractor paint like Sherwin Williams Pro Mar 200, or there are some specific "ceiling" paints on the market, like Ben Moore Muresco.

SirWired

 

[sirwired]

Oops... forgot to mention... if you roll (and you should, as a DIY in an occupied house), you will need to use a huge-nap roller. 3/4" or 1" should do the trick. A 3/8" will not work for acoustic texture.

SirWired

 

[sirwired]

You will need to prime over those water spots with an oil-base primer. Water stains unsurprisingly bleed right through water-base primers and paints. I believe original Kilz (about the only Kilz product worth buying) comes in a special ceiling-friendly spray-can meant for precisely this use. The paint mishaps are no big deal.

SirWired