Bridesmaid etiquette

Bridesmaids expect that they'll need to buy a dress. So what you're suggesting is fine. But I do suggest contacting each bridesmaid independently to find out what their budget is. You don't want to put them in a position they can't afford a dress, shoes, and anything else they planned on contributing.

If you expect them to pay you do have to keep the cost as low as possible and maybe offer to help out anyone who expresses difficulty with the cost. You might lose bridesmaids if you don't keep their budgets in mind.

It’s fine to want them all in the same dress as long as you can find one everyone is happy and comfortable with. You also need to ask them individually what they’re budget is and find something that fits in the lowest budget. However they’re obligation ends at the dress, if you are requiring them to wear a specific shoe and accessories you pay for and provide them. If you are ok with just saying “wear a nude shoe and silver accessories” then you can allow them to provide those things themselves and you do not have to pay. If you need to save money, you are not required to pay for their hair and makeup, you can make that optional for them to pay for themselves if they wish to use those services.

I don't think it's rude. But you do have to be mindful of their budgets.

I think this is mostly fine. If you want everyone in the same dress that's perfectly normal and fine and it's okay to have them buy it. However- please, please take their budgets into account. Discuss (preferably separately/privately and not in a group chat) what they can afford and what they feel comfortable with both financially and physically.
Paying for HMAU is correct since you want it personally done, good job there!
Generally the rule is anything past the dress is on you- this means shoes and jewelry. So, I think you should be paying for shoes if requiring a specific pair. However, if you found both a dress and shoes for the previously agreed upon cost I'd say that would be okay. Just check with your girls, maybe? I think jewelry should be paid for by you, as well, if specific and required.
Best of luck! It sounds like you are trying to do everything right and you seem very nice and considerate of your girls!

I more or less gave my girls guidelines and let them pick a dress. That way the dresses were similar, but not the same.

I think the same dress is still very popular. I would ask the budget individually before choosing anything. If you want to be nice you can ask if certain lengths or cut dresses are the preference for bridesmaids. For example my MOH is well endowed up top and I know would not ever go strapless, so I made sure to only look at dresses with straps. You want anyone having a meltdown about the dress, that'd save you some time and hassle later.
I think same shoes is okay, but you should be mindful of some people cannot wear heels, be sure to make sure everyone can wear what you pick.
Mostly check on the budget though.

I think having them wear the same dress is fine. Mine are wearing the same dress because I like things to be consistent. Most bridesmaids expect to pay for their dresses, but I would ask each girl privately what their budget is prior to dress shopping. I asked each of my girls and made sure not to select dresses that were out of their price range. As for the shoes/accessories, if you are requiring them to be the same I think you should purchase these items. Personally, I wouldn't make them wear the same shoes/accessories. I would hate having someone tell me what shoes to wear. I think you need to let the girls pick their own shoes at least because most people aren't comfortable in the same shoes. For my wedding, I just asked that they wear silver shoes. Some are wearing heels and others are wearing flats/sandles. They know what they are comfortable in and like. For accessories, I know I can't wear anything other than gold or my skin breaks out so if someone told me had to wear Sterling silver I would say no because I'm not have my skin itch and break out. I don't think accessories need to match. I know some brides require nails to match as well, but again I don't think that is necessary. I just asked my girls not to do anything too dark or wild.