It sounds like your 3 yr old cat has too much energy (which is why he's bothering everyone else around). I think you need to play with him more and maybe get a cat wheel or some-sort to drain all the energy.. Also, possibly getting more scratcher around your house may be helpful.
Also, you can...
I recommend scent swapping with brush that you used for resident cat. If your resident cat hisses when she smells, just place the brush where your cat likes to go and put some treats around it. Eventually, she will get used to her scent and be ok with smelling. Then you can try brushing her...
So it's been about a week since I brought a new kitten.
My resident cat is 9 years old, used to live with dogs most of her lives.
Anyhow, during week 1 of cat introduction, I've separated the new kitten for almost 3 days. Then, I let them see each other while focusing more on scent swapping...
Just a quick question. (It might sound little stupid)..but..
I am introducing my new kitten and my 9 yr old resident cat. Both are very affectionate. The resident cat used to live with dogs, and loves to greet people.
Anyhow, I live in one bedroom apt. Thus, the new kitten is being separated...