Wearables on Neopets have a small clothes-hanger icon surrounded by a circle in the bottom left-hand corner. Any item without that mark isn't wearable, and any item with it is.
You can only get wearable items from the NC Mall.
Almost anything that is wearable. Except for species specific clothing, which are few and are easily found on many sites on Google.
Look online for a full list of wearable clothing. I can't list them all here. If you go on one of the sites, there should be some clothing that has the word "uni" in it. They can also wear any other type of clothing, except those that have other neopets' names in them.
No it is not wearable. Check out jellyneo.com for guides in neopets (plots, avatars, wearables, etc.)
Is it wearable? It will be surroudned by a blue box and says wearable on the bottom of it if it's wearable. Also, if you bought it from the Unis clothing shop or something like that it will NOT be wearable. aside from the blue box, in parentheses it will say (wearable).
No.
* All neopets can wear wearble clothes
No.
neomall
A fantastic list of what neopets can where what on neopets can be found at http://www.neopets.com/~Echoh .
If the item is wearable, then it will say wearable under or next to the item's name in blue.click on it and there should be a thing that says try on click it and it will show what your neopet looks like in it but it takes it off when you leave
Search it up on Jellyneo's item database.