Oh, you ran into a big room. Those have monsters of all kinds. It's best to use a fast method of Perma-Elberething on the stair (like with a fire wand) or use a scroll of earth with a wand of striking to create an impromptu monster siphon. Doesn't work on giants however.
Also, scrolls of identify are probably the easiest to ID, since they're the cheapest scrolls (20 gp IIRC), and they're a tad more plentiful than other scrolls. Also, the other pro's might disagree with me, but I think you have your priorities wrong. ID scrolls first, then rings, then amulets, then wands, then spellbooks*, then potions, then any odd helmet you find, and then on your weapon if you're not sure of it's enchantment. Things like boots, gloves, bags, and armor can be tested very easily through other methods, and aren't worth wasting a scroll on. Scrolls are very important, and ID'ing the important ones will make your life MUCH MUCH easier in the long run. Rings are also important, which is why they're second, Ammy's are third, if only because finding life saving, ESP, or reflection is incredibly helpful, although it's important to curse test FIRST, to see if they're cursed, because if they are, then they are most likely to be strangulation or change, so just Call them something memorable and throw them away somewhere. The other things are also important, but can be ID'd through other methods as well. Don't ID spellbooks if you have no intention of learning a spell, or if you have plenty of holy water and can bless and learn easy.