My daughter is going into first grade, so I haven't had a ton of experience, but she did have 2.5 years of public preschool as well. First, the logo stuff. Recognizing logos is part of pre-reading. It teaches kids about using visual cues to figure out what stuff is. They don't actually endorse fast food or anything. Those are just examples of logos they might have seen. And despite never having been there, my son at 4 can recognize McDonalds.
So far the teachers have been great about respecting our values. DD is vegetarian, not vegan, but they know not to give her gummy worms on halloween or peeps around Easter and things like that. I have also worked really hard to meet them half way. When they were making gingerbread houses I brought in a ton of vegan candy for the class. For the most part though, I pack her lunch and it isn't an issue.
As for field trips that go against our values, we don't participate. They go to Sea World in third grade, and neither of my kids will go. When my son's private preschool did a unit on dolphins and whales, they talked about orcas. Of course he wanted to go to Sea world because the other kids talked about it. I explained in age appropriate terms that animals in captivity are not happy, and that we don't support that. He is 4, so that is all he needs to know for now. I then offered to take him whale watching instead, and we saw hundreds of wild dolphins swimming and just loving life. I know not everyone lives where they can just go whale watching whenever, but I would say to find a compromise or alternative experience that works for you.
Overall though, I would say this really has not been a problem so far.