Kitty with issues

Bit of a back story on him: I've had this guy since he was 3 weeks old, blue eyes and just getting his baby teeth in. He was found abandoned by his mother in a parking lot around the 1st of July 2007. I kept him seperated from my husband's older cat for the first few months to make sure he was healthy and eating properly along with using a litter box.

Now 4 years later, he still harasses my husband's cat to the point of pulling out fur, drawing blood and claw marks on her. He's done this since he was 4 or 5 months old. You call his name and he will take off knowing he's not supposed to be doing this (squirt bottle doesn't work either). He's not allowed into our bedroom just to give the other cat a break from him and give her a space to relax.

On top of all this he also has gotten into humping anything that he considers he can get away with. He had a small 2in plush lion when he was small to play with, at about 8 months old we hear him meowing and looked over to find him trying to mount and hump this little toy. I've since taken away this toy along with a dog toy and a monkey cat/dog toy because of this. He's now gotten to taking my daughters plushies and doing the same thing. As of last night/early this morning I heard him meowing again and remembered I had forgotten to put up a felt blanket before going to bed after work.He won't do it while I'm in the same room as him, but will pull what ever he "wants" into another part of the house and will stay there all day/night. Usually, he'll come sit in my lap or by my feet since he's very much attached to me but if he's gotten a hold of something he won't come visit at all. 

I'm just lost at anything to try to keep him from humping stuff or beating up the older cat. He was neutered back in Feb '08 and the other is spayed and about 7-8yrs old now. 

Crazy sounds about right, he's never been the typical kitten/cat. He never was content to curl up in my lap but rather on the floor next to my feet or shoes. I've never caught him with the bra or underwear, glad I haven't too! He does randomly attack, can be petting him one minute and next he turns around to bite and claw you with no warning.

He wasn't taken away from his mom, more found middle of the day around July 1st sitting in the middle of a parking lot,

We have plenty of toys and shelves to climb up on along with a laser pointer he loves to chase, while the female would rather have feathers. lol  I've been looking into Feliway, not sure if Rescue Remedy is avaliable here or not. Been trying to see if there's others that have had the same or similar issues and had Feliway fix it.  I have thought of using meds to help his bipolarness but would rather not have to spend so much on a vet trip at the moment. My husband also worried that the Feliway may affect the female's behavior in a bad way which is why I was looking at something that could be given to him.

I don't think its overly aggressive playing with him but more of he doesn't know when enough is enough and to leave her alone. The one growling and hissing is the female. I've seen them play and it's not the same as when this happens. Then again, they sleep at opposite ends of the couch or different rooms of the house a majority of the time.

Its more affecting his personality when he does find something to hump. He will stay at least a foot from what ever it is and won't come over for attention. He does hump other items when given his toy, its just gotten worse since he's going after other items. At one point in time he used to try to hump my leg while kneading it, I would set him down and ignore him for a few mins before letting him back into my lap.

I've tried some treats that was suggested by someone in town that has the same issue with her cat with no luck with the humping but he's less aggressive with the other cat. I just remembered the same time all this started my daughter had just started potty training. Could her having a few accidents cause this behavior to pop up with him thinking that she's marking his territory?