Finding it hard to deal with pups behavior

Hello everyone, I'm having some issues with Harleys naughty behavior the last few weeks he is now nearly 6.5 months old and I feel like I am getting to my wits end with him. Just wondering if any one can shed any light please. 

1. lead walking- For the last month or so me and my partner have fully committed on training him to walk nicely on his lead, we have used the stop technique every time he pulls and rewarded with cheese, sausage when he walks good and he was getting it for a week or so now I cant got more than a few steps without him pulling my arm out and its becoming frustrating because I know he can do it when he wants. He also is lunging out into the road when I don't expect it and I am worried he will get hit by a car. 

2. Nipping- He will chew the lead and when I am stopping or walking backwards because he is pulling on the lead he will jump up and growl nip me on the leg which I am inclined to think is frustration from me stopping all the time  I'm not sure. its so frustrating because what would take 15 mins walk around the block its taking 40 mins +. Every time he is nipping on walks I am sitting him and making him wait for a treat it works for a bit then he does it again.

3. Destructive behavior- Its like as if he is 8 weeks old again he will pick up anything and everything and he refuses to give it back just holds onto it. It feels as though he has forgotten all of his training

Just to add he is walked twice a day - morning he has a walk around the block on his lead and a run around on the common with his ball, then about 4 pm he has a run around in the field for about 30-40 mins. I just hope this behavior will improve as under it all he is a beautiful dog just very testing at the moment.

Hi, what kind of lead and collar or harness do you use?

Hi for the last few days we have been walking him on the collar as his pulls more into the harness but we use the harness if he's on his training lead. Both collar and harness are the Ezy dog

We have a 10 month old and we use a half check collar and a sporn non-pull harness with a double ended 6ft lead. As a rule she is very good using just the collar but when she decides to pull she's easily restrained with the harness. If needed she's then corrected through the collar.
I know of one other member on here who uses the same method.
Pete

Sounds like you are on the right track. They all go through a I don't want to listen phase. The biggest thing is consistancy and patience. He may also be teething at that age so plently of frozen treats

They do go through stages where they feel the need to forget and become stubborn. I understand the frustration of the lead walking as we still have problems with Bane and I can see if I stop because he is pulling too often, he does start to grunt and whine as is to say "Are you kidding come on I wana walk!"

Is it possible to be able to to get him out for another walk a day? Some dogs are more active than others. Or a quicker way to get him to the park so that he can run around and blow off some steam before you then try to do lead training with him? I know Bane always listens better on the way home from the park.

We also use a harness, collar and double ended lead too and this has helped so much with control Especially along roads

Thank you all for the advice and cheers Emma I will try what you said x