Cat skin and cats fighting

Question
I have 2 questions.  The first is we have had introduced a young cat about 7-8 weeks old to our 7 year old cat.  The young cat is now about 15 weeks old and the young cat is constantly trying to play with the older one.  The older one will hiss and almost bite the little one, and the little one is always laying submissively once the older one hisses and attacks back.  Is this normal behavior?  
The second is that the older one has scabs here and there on her neck, belly and tail.  Some are just bumps.  I wanted to know what they could be from.  I don't see any fleas with the flea comb and have been treating both of them with the once a month stuff just in case.  Also, the oldest was excessively grooming herself and pulling out hair.  She isn't doing that anymore.
Thanks for your response.

Answer
Hi Beth,

To answer your first question, not all cats are cat-friendly. Moreover, cats are territorial by nature. If you really want to keep the kitten, it may take a few months before the older cat is willing to allow the young cat in the same territory.

The older cat hisses like a snake to defence and attack if the younger cat is too near to its comfort zone. The younger cat is trying to tell the older cat that he trust the older one by laying submissively.

To answer your 2nd question, I would suggest that you bring the older one to a vet. She could be having some sort of skin bacteria and needs treatment.

Carrisa