If your horse is green, do you experience shying and spooking? How do you deal with this mentally? I need to learn some ways to work on relaxing through fear!
Do you mean how do you work through this mentally for a horse or for the rider?
To me green just means inexperienced in general or sometimes just inexperienced at what it is doing (although definitions vary), this means that a green horse might not be spooky at all and an experienced horse can still be very spooky.
Sudden movements or strange things are always going to surprise humans and horses but if you and your horse are confident then a "shy" is less likely to occur. The best ways to make your horse feel more secure is to be me more secure yourself, horses naturally follow leaders, so make yourself that leader, also, be firm, if they jump away pull them back together and keep moving, don't make a huge deal out of it, or horses learn to shy to avoid work etc.
As far as riding the spooky horse just keep your heels down and be alert, if you see something that might scare the horse don't tense up, but just be aware of the situation.
About 90% of the time when a horse acts like Pokey did its because of pain. Saddles can be difficult to fit to horses and no saddle will fit every horse. In addition, the saddle might not fit the same horse all year round, and may require adjustment. If I were your friend I would check that his back is not in pain, that his saddle fits and that the girth does not pinch him before presuming he is just being bad. You'll probably find that is the problem.
Also, I think you made the best decision passing on that horse. You should look for a horse more experienced in the disciplines you are interested in and a bucking horse is not for the inexperienced rider.
Good luck with finding a horse!