I know that no one will take as good care of my baby as I will. I also don't pay my babysitter much - she's a friend, so she's willing to do that, because it's all we can afford.
BUT
I'm not really comfortable with my childcare arrangement. It's hard leaving my child crying with someone else. It's worse when I don't think she's getting as good of care as she deserves.
Things that bother me:
1. The babysitter rarely changes her diaper. I'm talking about once in the six and a half hours I leave her, when my baby wears cloth.
2. She has other people watch my baby; my baby really is having a hard time dealing with the separation from me, and I think that by having rotating caregivers, it's makng that that much worse.
3. It's not an issue now, but the reason I chose using a babysitter (rather than daycare, besides the cost, is that I wanted one long-term caregiver) is that I really want to do gentle disciple and am attracted to the Unconditional Parenting philosophy. The babysitter has another nannying job. She complains about the mother not willing to use harsh enough punishment. Since the babysitter won't follow my directions on diapering my kid, I'm worried about her not following my discipline directions in the future.
On top of that T won't eat there (which is not the babysitter's fault at all, of course, it's just something that makes it that much harder), I feel REALLY bad about leaving her. I just don't know what the likelihood is that I could find a better caregiver, and I don't want to go through a bunch of them, because T really needs to form an attachment with someone to make staying with someone else easier for her. I'm particularly limited to what caretakers will take very little money (I pay less than half the lowest rate I see in ads for babysitters.)
Should I try and change? Should I lower my standards?

Having a childcare provider who doesn't respect your requests as a parent is a huge deal. Your standards aren't too high. The fact that she is not on the same page as you with regard to discipline is going to be a real big deal as T gets older.
I would keep using her for now, but search out other options, which may take a while with your financial limitations.
I agree with CanadianMamma,
I think that you are seeing little red flags, and if I were you I'd start searching for some other options. I don't think you can ever have too high of standards for childcare, personally.
I also agree. You are the parent and it's up to you to decide how you want your child raised! If she can't follow that then she doesn't need to be watching your kiddo. I would start looking now. You never know sometimes you get lucky!
I agree with PP start looking for a new caregiver. The problems you have with the one you have now, are not small. You need to feel comfortable leaving your child with them. If you have a feeling that something is not right, it probably isn't. I mean really how difficult is it to change a baby's diaper? Not that hard. Honestly. If you have a feeling she wont listen to the way you want to discipline your daughter, than that is a definite reason to switch. If she has a different way of dealing with her than you do, your child is just going to get confused. (This is okay here but not at the babysitters?, or if i do this here i get a time out but if i do this here i get {enter another type of discipline here LoL}?) All in all she is going to forget what she can and cant do at your house and at the babysitters, and she is going to get different punishments at both places KWIM? It is important for you two to agree on discipline styles. I don't think your requests are overboard.
It is totally unacceptable, in my opinion, to leave a baby for an extended period of time in a cloth diaper. I would look for another sitter. Or, if you REALLY like her (which it seems you don't) switch to disposable for the time she is in care. I had to do this for health regulations with my son when he was little. It actually made things a lot easier.
Also, if she won't eat, it may be partially because the babysitter doesn't know how to get an attached baby to eat, and it sounds to me like she may not be giving enough attention.
I agree with the pps about finding a new sitter. I know how hard that can be though. It's hard to find someone you feel comfortable with at a price you can afford. I am right in the exact same boat. Do you have any family members that you trust who could care for T for few hours, like grandma, aunt, or something? Maybe until you can find someone else.
If you have family, that would also probably be better on her too. If she is close to them, then she wont feel so bad when you leave.
From my point of view, your standards are never considered high. It is what you want for your child and that natural instinct of motherhood occurs. Keep searching and you will eventually find someone who respects your standards.