For Arabian

You know how you get Arabian halters instead of regular halters. Well do you get an Arabian size headstall and bit? Or do they not make them in different sizes like that? (her face isn't that strong of Arabian) It's my first horse and no one has ever really taught me about that type of stuff. Oh and you know how they have a bit that has the same name but there are a ton of different ones? What's really the difference?

I have an arabian/quarter cross so i'm guessing she might have the same type of face/head as yours (small but not as small as most arabians).

I buy my horse arabian sized halters and flymasks and they fit good.
When it comes to bridles and headstalls, the "cob" size fits her rather then the standerd "horse" size. Having to do with the bit, she fits well into an 4-1/2 inch rather then the standerd 5 inch. Maybe this is what you mean by different bits?
Hope this helps

I ride ONLY Arabians.

Buy Arabian sized halters
Buy Cob sized bridles
Buy 4 1/2 inch bits (for most Arabs those fit the best)

For bits the differences can be:
Brand
Size
Type of metal
Thickness
Jointed or solid in the middle

There are Arab bridles available. It's up to you though if you want to go that route. You could get a regular headstall and put in more holes if it needs adjustment. Try a few friends bits if it's available before you buy a special size.
The different bits - there are different variations on a snaffle, I"m guessing that's what you're referring to. Mostly, it refers to the different 'builds' of the bit. BIG differnces in how they apply leverage, and the levels of severity. Ask the person who had the horse before you what bit they used on the horse. It will save you lots of dinkin' around with a million bits.
Oh, and congrats.

Thanks a lot guys :). Yeah I did mean the inches (I searched more and found out about sizing afterward). The previous owner has a snaffle bit for her but she had to use a lot of force to get her to do what she wanted (she would only ride on the weekends). She has a lot of go and doesn't like to stop. So that's why I'm switching to a different bit. Everybody at the barn is telling me to get a Tom Thumb bit. At least for now till she learns to stop and turn when I want her to. I have soft hands so if the Tom Thumb bit is considered "harsh" I'll be real light. Oh, and what Tom Thumb bits would you suggest? There are so many different ones my head is spinning . I'm just wondering (cause I don't know) what does the roller do on a bit?

Switching to a harsher bit may not help the stopping problem. You'd be better off working with her more, rather than switching bits right off. She may respond better to you if you're better with your seat than the other owner was. Don't let her trot with you until she stops well at a walk - and when she does stop, make her back up a few steps. It helps to reinforce that whoa means cease all forward motion, not just pause. Then progress to the trot, etc....
As far as what style of tom thumb - really, try working with her first. Even if you're soft, the harsher bit can screw them up if the other cues aren't very clear, and understood first.
When you're ready to move up to a tom thumb, the snaffle part of it should look the same as the one she's using, just with shanks on it.

I do the leaning back thing when I ask her to stop. The lady who rode her before did that too but she'd end up having to do emergency stops all the time. The lady wasn't the owner (the owner had a ruptured disc in her back (or somethin') so she couldn't ride) so I don't know if she would have wanted to get a different bit but couldn't (cause she wasn't allowed). She's 17 so she knows exactly what I mean when I ask her to stop she's just being stubborn.

Ok I'll try that. She usually just keeps going even if I'm asking her to stop. She's really stubborn and even if you try to turn one way if she wants to go the other way she'll just keep going. The bit she has now is some kind of loose ring snaffle bit (I think) with no curb chain and everybody I've seen riding her has the reins up tight like english riding. I ride western and I don't even know how to ride english. The first time I rode her I didn't realize that it was like an english bit or whatever it is so I was riding western and it kinda seemed all loose in her mouth. I'll try doing the stopping and backing up stuff. With english you just hold the reins tight enough so there's no slack? I have no idea cause the lessons I'm getting is western and he's always scolding me to keep the reins really low and loose.

Oh yeah I just love your boots! They look so nice! Good pic :)

Yeah, with english you ride with a much tighter rein. And western im sure you know, you ride with a much looser rein. BUT... my pony rides english and western, but with an english bridle at all times. She seems more confident when I ride with a tighter rein. SO my point is... don't be afraid to use a tighter rein with your horse even though you are riding western. And if your horse needs the more tighter rein, don't be afraid to use it.

Ok I'll try that. Thanks guys :)