I want to say first off that I am far from an expert in either discipline and have never competed in either. These answers are just what my gut tells me and from what I have heard from others who did compete.
1. Neck reining, lateral flexion, leg yeilds, flying lead changes, etc. Anything to give you more control over all parts of his body
2. No idea. ;p
3. Once he is very supple and willing, start by walking the pattern and SLOWLY work your way up to a lope. I have heard that it is best that you only run the pattern flat out 1 time every couple of training sessions. Doing it constantly at high speed with increase the risk of injury and will speed burnout and sourness.
4. I would say work on the pattern no more than 20 to 30 minutes a day. Or, if he has a perfect run 5 minutes into the session, stop then. It is always a good idea to end on a good note.
Bending: (poles I assume?)
1. Again, no idea............Sorry. :)
2. I think they are supposed to be 21 feet apart.
3. Same as #4 above. I would also not practice both on the same day. Just mix it up and keep things new. Do barrels one day then trails for a couple of days then poles.
I think it would probably take a little longer to train him thoroughly doing this but in the end, I believe that you would have a happier, saner horse to ride.
Also, don't insist on doing the pattern every time that you are in the arena. Sometimes, go trot and lope some big, slow circles around the whole pattern to warm him up before a trail ride. This will also help him from getting arena sour.