I'm dashing offf a quick answer, it's late here and I have to get to bed.
A few points - what you describe is VERY familiar. I have a family full of these, with a easy child in there as well to tell me that it's not my parenting, it's just how my kdis are made. However, we've been able to make a difference too.
Kids like this - they are babied because it's what they need. You can help them towards maturity but only at a rate compatible with t heir own much slower rate of maturation. They take a lot longer, but with support they will get there, or at least close. Interest in girls - don't push it. If he's gay, then he's gay already. Chances are he's not, he's just not ready to think about it.
The undescended tgesticles - independent of the autism, but needs to be dealt with as a matter of urgency, for long-term health reasons. It should have already been dealt with.
Kids like this are a puzzle, but the one HUGE bit of advice I can give you - change your mindset. I'm not saying here that you are being hard on him, just that because these kids' brains are wired so differently, we need to constatly watch ourselves that we're not expecting them to 'tick' the same way the other kids do. But it IS possible to get into their heads, it takes time and a bit of digging (and picking the brains of those who have gone before - plenty of us here).
Example - if a 'normal' kid behaved the way ours do (such as hitting back when other kids bully them) then we'd punish, and thereby get the message across. But to punish these kids the same way,sends the wrong message andcan reinfoce the very behaviour you're trying to change. You CAN modify the hitting behaviour, but in a totally different way.
Read "The Explosive Child" by Ross Greene. There are some good posts on this already (in Early Childhood forum for example, although he's older than this).
For specifics - we can help there, too.
But he is going to need supporting, a gentle hand, a lot of love and patience - and he IS capable of giving back the same love, too.
He's getting pulled from here to there, from this household to that. He's confused, scared, NOT lazy in the way you think but more likely to be fearful especially of change and especially of change which he is not permitted to have input into. Kids like this need to feel they have some control or ability to predict what is going to happen, they don't cope well with being dragged here or there with little notice. They DO respond very well to you behaving toward them, as you want them to behave toward you. Routine is important.
You say he seemsmentally about 10 years old - that's typical. I describe my 15 year old autistic son as being like a 10 year old genius. In some ways he seems even younger; his best friend is another autistic boy who is 10 yearsold. Another close friend is a girl of 10, a VERY bright girl. A nearby neighbour who often asks difficult child 3 to play, is 8 years old. Kids his own age - they try to converse with him but it's like pulling teeth. He's just not capable of holding aconversation unless it's about what HE can talk about (computer games, mostly). But yesterday there was a study day at his correspondence school (which means the kids go to school for a change and work in a classroom together). difficult child 3 teamed up with a bright girl of 15-16 and was teaching her how to compile a powerpoint presentation. He then helped the other students work the interactive whiteboard to demonstrate their powerpoint presentations. There was a problem with one of the computers; difficult child 3 stepped in to help fix it in time for the teachers to demonstrate some technology to the class. He did really well - and then last night threw a massive tantrum because he couldn't let a topic go, and couldn't understand how we were trying to find a good solution to a computer problem that has been bugging him.
difficult child 3 is also showing a very delayed interest in girls - the girl he was helping yesterday slipped him a note which said, "I think I have a crush on you," and difficult child 3 was grinning a sheeping, wry grin. However, he's not ready for it to go ANY further.
difficult child 1 had a girlfriend from about 13, but SHE did the chasing. And at 15, she had outgrown him and broke up with him. He was heartbroken and suicidal for 2 years. He then found another girlfriend for a few months, was not quite so heartbroken when they broke up and then almost immediately attached himself to another girl he met. They were boyfriend-girlfriend for two years and have now married. He is still immature, still needs a lot of support, I worry about her workload because in some ways he is a husband but in other ways he is her child. And there are times when SHE needs support and for him to be strong, and he is still learning how to do this.
Your son will need time, will need you to model good social skills for him and will need you to lead the way, not push him.
We can help. I'll be back in a day or so, maybe 20 hours' time when I've caught up with Life!
Meanwhile, welcome to the site, you're in good hands. So is your son, he has a dad who cares for him - because you're here. My husband (Marg's Man) is also a member here, he will be around before I will be. He can give you a uniquely male insight into fathering boys like this.
Marg