Well, we started talking about eyesight and Miracle-Mineral-Supplement , and I've managed to drag you over to a discussion about having your teeth replaced...lol.... Actually, you may or may not be highly susceptible to mercury poisoning, because many people excrete it normally.
That doesn't mean that it has no effect however, and if you can afford it, that would be a top priority on MY personal list. Sort of like going to the doctor and saying "Doc, can you recommend a good skin lotion?" And he looks at you and says, "certainly, but what would you like to do with this arrow sticking in your head?" You really won't know what you're enduring with amalgams, until you get rid of them.
About the time required for chelation... You get faster results at first, so you make your biggest improvements soon after removal of the heavy metals. ALA is great as a chelator because it's CHEAP, non-prescription, does other good stuff for your body, and most importantly, crosses the blood brain barrier.
I don't know why you're taking magnesium (our reasons were over/under methylation blah blah blah) but Epsom Salts in a bath worked better than transdermal cream when we were using it. It's just not as convenient.
I've never wanted to be particularly knowledgeable about medical stuff, but have been dragged kicking and screaming to lengthly experimentation due to my "hellth" and have seen good improvements over time. But it's difficult to get good results if you have too many variables going at once. Keeping simple informal records will help you a lot, and before you get Amalgams out, you might want to stabilize your routine so you can tell what difference it makes when you do.
Let's see now, what other threads can I hijack? :)