help with a standard bred? please

Hi
My mum has recently brought a very quiet standard bred he is 14 yrs old. He has for the last 2 years not done very much at all only the occasional trail ride around some quiet roads that are very flat and even. Before this he had done pc and a couple of encourage shows and a little jumping but this was around 4 yrs ago.
So here is the problem or should I say problems...
Firstly he doesnt move away from pressure, eg even when on the ground he wont move his quaters over when asked he just stands there or leans against it. This mum has been working on with lots of ground work asking him to move away, with parrelli style methods
Secondly as he wont give to pressure he doesnt bend at all on one rein and the other is very limited. He will soften his neck and stretch on the straight but he really leans on the inside leg and refuses to move off it
Thirdly he will only trot not pace on flat straight ground... I can get him to trot on a 30 mt circle on one rein but only if he is strtching his neck and not leaning on the inside leg.
He is not forward moving to your legs but better with leg and voice and is very responsive downward trans, I just sit or think of sitting and he will come back.
The people who did pc with him said they could canter him and he trotted but it took a while for him to get the hang of it all so I know he can do it I also know I have to fix these thing before he will go straight into trot and later canter but what do I start with first as to me they are all equally important.
Any advise would be greatly appreciated
Teri
Ps
He has also started to stop while out on a trail going down hill, I suspect that as he was in a small flat paddock with no work at all for at least the past 12months it could be musclular and have booked a chiro but he wont be here till next month, any excersise tips that could help with this too would be great
Thanks
This is him

I've started Hill Therapy and it is helping my horse well. Find a small incline and lunge him over it, five minutes walk and if he isn't struggling try a trot for a minute or so, do this every day for a week and then do five minutes walk trot each day. The third week you can add in a few minutes of canter if you think he's ready and not struggling (huffing and puffing at the trot/walk) Once you can do that find a steeper incline.

www.parellisavvyclub.com/media/hilltherapy.pdf

As far as the pressure goes, get your carrot stick and just work on him giving, go to phase four if you have to and just hold and let him move off the stick, then give him a good thirty seconds to digest that before trying it again, just rub rub rub! For thirty seconds all over and then try to get him to yield the hindquarters again.

I say quit riding him and get on ground work, do lateral flexion with him in each direction until he can do it with the slightest touch of the rope. http://www.youtube.com/watch?v=hQQZGasPE6c Do that from the ground first, you may have to walk in circles with your horse for ever but it will be worth it.