Do the colonel in the cavalry have their own sergeant under them?

NO THEY HAVE A HORSE UNDER THEM!

No, if they're in the cavalry, they'd have a horse under them.

If you mean like an orderly, no. Enlisted are not used as valets these days.

Don't-Ask-Don't-Tell was repealed so I guess you could ask one.

Your question doesn't make a whole lot of sense.

And a Lt Colonel, a Major, a Captain, 1st. Lieutenant, 2nd Lieutenant, Sergent major, 1st Sergent, Master Sergent, other Sergents

No, not at all - that's a horse.

No. That's a horse you're looking at.