About the brush thing, you're absolutely right. With my horse, I took whatever he was scared of, to his nose (or the nose to what scared him), until he was comfortable with it. So try throwing the brush after he smelled it, from his nose to the porch, that might help.
When he's trying to go somewhere you don't want, there are 2 things I usually reccomend:
1 - you did it, put him into a circle until he stops, then take him the way you want. Do it as many times as needed, until he understands he is not the boss.
2 - work a bit harder before going out with him, make him a bit tired, so even if he pulls somewhere he won't be as strong, and the rider has more time to react (very usefull with kids and new riders).
Besides this, you can only be pacient. Horses are a bit like people, each one reacts to the same thing in a different way, and takes a different amount of time to learn new things. So take your time, get to know your horse, and in a few months not only will he have stopped this, as you will be able to predict these types of episodes by the smallest changes in his behaviour.
Hope it helps some ;)
"There is something about the outside of a horse that is good for the inside of a man. ~ Winston Churchill"