CELTA is an introductory teaching course, so when you apply, keep in mind that the tutors understand you will probably have little or no experience. That's fine. What you will need, however, is to be willing to put in the time and effort to look through and find resources, help, and guidance to questions you face (and asking on a forum does not count ;-)). The internet is full of resources, and there are many great books that can help you prepare.
Here are some hints for you, though, on your questions:
Do you know about word stress? Here's a guide that will walk you through this concept, from counting syllables to noticing the stress:
Word Stress You should be able to complete that part of your assignment yourself after you finish. (Hint, hint, in the future, if you get stuck on something sneaky like 'vegetable' or 'comfortable' there is a super common reference book/app. Think about it and you'll figure it out... If you wanted to learn more about a specific word, where would you go?)
For pronunciation problems, you might want to think about who your students are, and what their first language is. What are common pronunciation difficulties for speakers of that first language, and how would it apply to the words you listed? If you've never been with non-native speakers and have absolutely no idea, try a Google search for common ESL pronunciation problems of such-and-such speakers. Keep in mind there's not really one specifically correct answer for expected pronunciation problems that the tutors will expect you to know. When you're preparing your lesson plans and language analysis sheets (you'll learn all about those in your course!) you'll need to note what pronunciation problems you expect your students to have. Your tutors will help you refine your expectations over the course. For now, just use some critical thinking and try your best.
Remember, the internet is your friend. Do a search first, try several different keywords, and look for a couple sources. Think about investing in a few go-to books. (I'm sure people would be very happy to share their ideas on this!) And don't panic!
