Not sure what to do about makeup

It sounds like you already know what you want to do. I personally think having two separate artists is better, especially since the hair stylist is ALSO a BM and will need to get ready herself and that will eat into her time if she is doing hair AND make up for everyone else.

Since you would have the pay the professional artist I would just tell your girls you have decided to Hire MUA X and the price is X amount, whoever wants to have it done is welcome to get in on the service. Most people are picky about their make up and may opt out to do it themselves whether your friend does it o the professional does it. Of my 8 people who got ready with us, only 3 BMs and my mom got their make up professionally done and everyone else opted to do it themselves. All five of my BMs opted to have their hair done though so I would just give your girls the option for both and see how many people that actually is.

ETA: also you need to think that hair will take about half an hour per person and about an hour for you, and the same with Make up. So if you have one person doing both that is an hour per person plus two hours for you, which you need to work into your timeline to be ready at the right time pre ceremony - especially if you're doing any photos before hand or a first look with either you H or your Dad. Having one person affects the time you need to start getting ready. Having two people - one for each service - streamlines this. I also highly doubt your BM will be offended if you explain that its a timing issue with hiring a MUA.

If it were me, I would ask your friend's mom to do a trial and explain the situation to her. I'd let her know you love (if you do) how she did your makeup, but you don't want to offend your friend in cosmetology school. Then do a trial with your friend and if you don't like it hire your friend's mom. If you do, let your friend's mom attend as a guest. Another option is, you can have both of them doing hair and makeup because getting ready will go by a lot faster.

I would pick a vendor over a friend — less feelings will get hurt the day of if you have suggestions. And with a vendor, you're more likely to have a contract, whereas the friend may not write up a contract and is free to back out the day of, even if you don't think she would do that to you.

If it were me, I wouldn't wait. I had one trial already & it was bad, I contacted someone else and she was already booked. My wedding is this coming April. Do a trial now and make sure you like it, don't wait on anyone!

I'd choose the vendor over a friend and explain that to her. I wouldn't hide it at all just explain your concerns.

Ohh this is tricky... if you wait until your friend comes to town to do the trial and you don't like it, then you might hurt her feelings...

I would honestly tell her thank you so much, can you please do the rest of the bridesmaids, and have your mom's friend do yours and say something like you don't want her to feel rushed for time to do all the women there. It is not weird to have someone to come dote on you only on your wedding day! If anything it's a very valid excuse! Do what you will feel most beautiful with because at the end of the day you want to feel comfortable and gorgeous from now until the wedding.

Personally I would go with the MUA who told you about your foundation and she's professional. Since I'm picky about makeup. Your BM can do your hair if you choose.

Go with your Mums friend. Less stress on the day. Your bridemaid can do all the hair, that will take long enough in itself. Imagine you don't like what your friend does on the day.... better with a third party

Have you considered having your mom's friend do your look and then your bridesmaid do everyone else's look? You could just explain to your bridesmaid who is the makeup artist that you don't want to feel rushed or anything if she were to do everyone's look, because keep in mind your makeup is the most important on the day!!