Dear ETran,
I agree about checking her ears and also that she might be cutting those molars. But, no one seems to mention that she may be super frustrated with her lack of ability to communicate. My 16 month old understands almost everything we say to him but he still only has about 10 words that we can understand. He is clearly frustrated by this so we are using Baby Sign Language with him. It really, really helps during the day if you can have your daughter be able to help you know what she wants. Some of what she is doing sounds like a regular temper tantrum - and tantrums can start as early as when they turn one. They know they want something that they don't have but they can't tell you what it is - so they cry, kick, scream, etc. Look at some of the baby sign language videos and see if that helps. Your 3.5 year old should be in the "love to be a helper" stage - so maybe he will help you with using the sign language with your daughter.
Try feeding your daughter with your 3.5 year old if you are not sitting down to family meals. They should be eatting the same thing anyways - and she needs to be in a high chair at her age.
Good luck - parenting is a tough job! C.