My opinion is that those other dogs shouldn't be loose around yours. Not if they end up like they do. But with your friend's dogs, you might not have had a problem if the ball hadn't been there. I'm always very wary when other people have a ball at the dog park, because this brings out the worst in some dogs.
Once you get the trainer, you can work with Varek to be less recative but considering his past experiences, he's entitled to his attitude - so now you just have to work harder to change it, lol. I would pay no attention at all to the dogs you pass on walks, just walk on by without a word or acknowledgement, and don't let them get close enough to start something. Some people think that's being rude and snobby, but you have to put your dog first. If roaming dogs are something else you need to worry about, maybe a nice walking stick would come in handy.