I find myself recommending this site a lot now for those who want to start training, or picking it back up again. It is a free site and they start with the very basics, and go up to competition or show training if you wish.
Introduction | Mind to Mind
We got Mario as a 1 yr old, and he was not trained to do anything before we got him. He now knows about 25-28 commands in less than 6 mo. I have trained dogs all my life, so I used that above site mostly for task or pre-task training skills, but I did review the basics before I began recommending it.
The humping I am not sure you can do a lot about. Maybe provide an appropriate object for your dog ie stuffed animal or blanket. FYI, I have read more medical benefits to neutering than risks, but finish your research and then make your final choice.
I would start on basic obedience and shore up his leash training so you can take him for walks. I hear that cures a ton of behavioural issues for a dog, including barking.
Biting your toes, I would just do a firm no every single time and praise/reward when he stops.
There are many methods for leash training. Consistency is the key, and likely he will fall in-line fairly easily once you choose a method and implement it faithfully.
A pretty good book I am reading is "A dog who's always welcome."
Good luck, and keep at it. Older dogs can be trained almost as easily as younger ones. I am currently doing some retraining on our Airdale who is 5.5 yrs now. He thinks I am nuts, but he is humoring me none the less
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