Do i need so many different wallets, or is it enough to have just one?
One is sufficient. I'd recommend 2-3 wallets if you're holding significant sums but I doubt that you do given your knowledge.
The next question, do i pay fees to transfer from and to my wallets?
Yes. You need to stop thinking of the old definition of a 'wallet'. In Bitcoin it is just a collection of keypairs that makes it easy to use Bitcoin and interact with your addresses. When transferring the *between Bitcoin wallets*, there is no concept of ownership, so whether you're transferring from your address to your own again, or from your address to someone elses, doesn't matter. You need to pay fees.