- Recall - great he knows what to do and you have trained him well - you now need to do the crucial bit and add in distractions. This will take time and can be frustrating but if you are prepared for hard work and consistency it will work.
Have you got DC's or someone else to help with this. Get one person to hold the dog and you run away yelling excitedly the dog should be pulling like crazy to get to you call the dogs name and come the other person lets the dog go. Do the same the other way around. This encourages the dog to see the excitement in the recall if you do this enough it becomes natural behaviour.
Also once the recall is fun and fast again start to add in distractions so the same thing again but maybe have a third person standing nearby, the dog should run straight to you. If that is too easy have the third person playing with a ball, holding some food, with another dog etc.
Being a gundog a furry toy may be the ultimate distration so build up to that - when the dog can be recalled from that you can move onto trying with the real squirrels and rabbits.
If when out on the walk the dog will not come back do not call just sit and wait it out. You do not want him to learn again to ignore the recall.
You could do this with a recall command or a whistle.
2)Spaniels will often pull unless taught otherwise (what a sweeping statement! prepares to be proved otherwise by all spaniels owners 
).
Again you need to break this down. If the dog can not walk to heel in a calm boring environment then it will never do it when out on his favourite walk.
I clicker train the heel off lead in a safe place usually the garden. Lure to the correct position and click and treat every few steps. When I introduce the lead it must be loose so if the dog walks ahead just stop and wait eventually the dog will look at you , click and treat and then lure into heel position and off you go again.
The turning around can work but does as you say spoil a good walk. I train heel as a trick and do not even try to introduce it onto walks until they are good in a boring place. Once it is conquered in the garden try in a carpark, try down the street etc.
3)Jumping up at people is this off lead on a walk or in the house? It is always the peoples fault here! If everybody would just turn their backs on dogs as the dogs jump up there would be no problem! But most people either fuss or say it is fine! When the dog jumps up turn away and cross you arms everybody has to do this when the dog is sitting then praise and fuss the dog.