1- Certain verbs are rarely used in the progressive form: like, want, need, love, hate, understand, etc. They are often connected tofeeling, thought and emotions.
2- Not that I know of, sadly. There are some rules, but they are incomplete and so full of exceptions that they don't cover the language as a whole. If you see a new multisyllable word, do you know where the stress is? I don't- I thought 'episcopal' would be stressed on the third syllable until I was corrected.