DS is now 6 and doesn't understand as much as a normal 6 year old. A current example is he's going to daddies for Christmas. He understands Daddy and what Christmas is just about, (1st year he's been into it) but he doesn't get the time scale and keeps thinking its in a week. Anything past a week doesn't exists. A year ago roughly anything past tomorrow didn't exists so its an improvement.
As for simple instructions it depends what it was. We had a chart of instructions for everything, and I mean everything. From getting up with breakfast/bath/teeth etc and for going out so that was shoes/coats/car etc, They where pictures on velcro so he could take them off once he completed the task and posted them as he loves posting things. I will admit it very time consuming but helped no end. One day I told him we're going out and he just started trying by himself. I think he was just over 3. He still can't get his coat and shoes on, but has a good, but he has managed t-shirts and jumpers on/off by himself. He is also working on leg holes in pants and trousers, but he can pull them up.
As for feeding himself, he can do it, but choose not to if that makes sense. We will sit at the table with tv and computers off, but still likes mummy to help. However, when at school or a restaurant he will fed himself with only the usual pea/beans issue with the spoon he needs help loading. I'm at a loss about how to fix this as I want to eat too
I tried leaving him to fed himself but he'll do two mouthfuls then claim he's full even when he's not. I've even left the table leaving him to eat for himself but even if he sits for an hour he'll eat nothing. They say children won't eat if not hungry, but autistic children are different they have been know to starve if not fed the usual foods. Thankfully my son isn't a fussy eater. Drinking wise he likes bottles with the children's lids or sports bottles. He can drink from cups from about 3, but bottles are easier for him so we keep a stock of bottles and just reuse them until they get disgusting (they are washed in between of course) but he chews them and there can be a lot of back wash and I end up wondering how he gets xyz in the bottle, so do go.
I'm guessing toilet training is far away? DS has been dry for just over a year now, so when he was 5. His paediatrician was fine with that and said he's seen boys just learn over night and was quite common to still be in nappies until 7.
All autistic children, like normal children learn at a different pace. So instead of overloading him with every routine or thing you want him to learn focus on a couple which are important to you, then once he's comfortable, with them add another one and so on. He doesn't have to have learnt it, but got the rough idea and is ok with you doing it with him. He'll be learn other things as well as these basic skills through play, speech language if he has that and other things you may do. Another thing which worked for my son was to make a song about what he needed to do. So for example we just replace the words to mulberry busy song to This is the way he brush our teeth/get our shoes etc. He responds really well to music though and has recently started piano lessons. He's far from a musical prodigy but for the time he enjoys I'm going to let him have fun.
hope that was a little bit helpful! Feel free to pm me if you have any questions 
