I also agree that talking alot is pretty normal for a 4 year old. However it sounds like you need some practical strategies to help you out! Do you have a designated quiet time? Normally after lunch is a great time for this, some books, quiet games/puzzles, etc in her room for an hour or so to chill out - for both you and her.
Talking in the middle of the night isn't really normal, nor is consistent broken sleep. Have you talked to a child health nurse or practioner about some practical tips and solutions for getting her to have un broken sleep, etc.
Is there a reason for delaying her start in the pre prep program? This will certainly give you some break time as well.

I agree that you need to seek some professional help.