Although Sifu is the main teacher, a lot of other students are showing me the form. Is it possible that I could have only Sifu teach me? I think I would make better progress.
Probably not, although you can arrange for private lessons with Sifu. While Sifu is always here to teach beginners, the students who help are all high-level practitioners who know the form well. They are learning to teach. It is part of their training and Sifu is helping them learn. If there is one particular student teacher you would like to work with consistently, just talk to Sifu about it. Similarly, if you'd rather not work with an individual, tell Sifu.
I am 73 and know I learn more slowly than some of the other students I see in class. I feel a little like a burden and kind of inferior. I don't know if I will ever make it through the 108 form.
Thank you for being here. You are a wonderful addition to our school. We welcome young, old, slim, hefty, rich, poor, all kinds. We all learn in different ways and at different rates. Just keep coming to class. Be persistent. You will finish the 108 form in time. Sifu always says, "Learning more quickly doesn't mean you're a better person."
When Sifu or a senior student corrects me, I feel defensive and as if I'm not doing very well.
When you receive a correction, it's actually a good thing. It means that whoever is teaching you thinks you are ready to do things more accurately. Eventually, hopefully, you'll be saying "thank you" and really meaning it!
Sometimes another student corrects me, and I'm not sure s/he's right. What should I do?
Students should not be teaching each other, with the exception of advanced students whom Sifu has designated to help with beginners' classes. If you are uncomfortable about anything going on in class, do talk to Sifu.