I understand your concern. I teach at the university level, and we are constantly asked about our credentials (not as often from students, but we can hang our degrees in our offices so they have that info too, and some places publish it in the catalog). At the elementary level, especially kg, I think her personality is going to be more of an issue. I don't think it's as common to ask them about credentials because the school district will have strict hiring requirements. But if you are not sure about your child's experience in her class, I think you are absolutely right to keep abreast of the situation.
Stay as positive as possible--you need to get good info from the teacher without her feeling attacked. If you can schedule a conference, do it. But focus it on your child. Just tell her you want to make sure he has a good year, so you want to talk early about his learning style, etc., and ask questions (non-accusatory ones) about how they liearn this and that, and if there's anything unique about your child (i.e., gifted, has trouble in a certain area) you can ask how the two of you can deal with it as a team. While you're there, if the conversation is going well, you might get on the subject of experience, but I'd let it work itself into the conversation. First-year teachers can be very motivated, excellent teachers; those close to retirement can be experiencing burnout. That is why her actual credentials might not be helpful--they could actually be irrelevant.
My guess is that if you treat her as a team member while talking to her, you might get farther with her.
At the end you could mention your notes. Again, you don't want to attack her, so you might say that it's the beginning of the year, so you understand that she might not have her schedule for volunteers set up yet, but you'd love to come into the class to help. My daughter had kg last year, and when I asked about volunteering, they didn't seem to need my help--there really wasn't anything they needed help with. I had signed up to volunteer for a class party in the school office, but when I asked the teacher, she said "well, you can come if you WANT to, but we have everything taken care of. However, when I offered to do a presentation on the Moon Festival (my daughter is adopted from China, and it's an Asian holiday), she was very excited. So SHE didn't really have ideas for me to volunteer, but when I had one, they were all over it and the kids had such a good time. They even asked me to come and do another one, so I came back and did the Qing Ming festival in the spring.
So if she says there's nothing, you might go with an idea or two of your own for something special.
Good luck. I hope your son can have a good year after all!