Ok, let me try to answer each of these:)
-I have some old equestrian riding pants that I was wondering if they were okay?- You can wear a "flight suit" that is two separate pieces, or a two piece set up. "If using two separate pieces, they must give the illusion of a one piece flight suit by using the same color and material for each piece." So if you use those pants you will need a top that matches them pretty closely so it looks like one piece.
-I also have boots and half chaps- boots are required, half chaps are not, but you could potentially wear the chaps over your flight suit if you wanted.
-Also if I were to do a one-piece suit could I just use a jumpsuit? What kind of jumpsuit? A flight suit? Yes. Coveralls? Yes. Spandex bodysuit? Yes.
-In regards to the vest can I use a lightweight padded vest?- Yes, potentially. It would depend on how lightweight. "Vest fabric must be thick enough to support armor plates without sagging, creasing, or wrinkling and be constructed from quality fabric. Suggested materials include cotton or cotton twill, nylon, duck cloth, leather/imitation leather, or quilted fabric. Stretch materials may only be used if they are form fitting and reinforced enough to support the armor plates without sagging." (from the CRLs)
-Are gloves required? Yes
You should take a look at the CRLs, they are very well laid out and will address most of your questions:) You can find them here:
http://mandalorianmercs.org/get-involved/costume-requirements/