First, I'm not a big fan of having a home that's already sided w/asbestos cement shingles being 'encapsulated' by 'new siding' (like vinyl). I'm a fan of having the siding removed first, THEN resided.
Soooo, you asking, what does this have to do w/your questions? I'm just looking at the bigger picture here and offering some info to others that might be considering covering their asbestos siding. I don't think it will be long before a home owner will be forced, by law, to disclose ALL sources of asbestos in/on a house. They call it Seller Disclosure. And don't think that you can get away w/saying you 'forgot'. Although asbestos cement shingles are, essentially, harmless in a non-friable state, it DOES pose a potential danger when it's friable. Non-friable = solid state; friable = 'breaking' it up (whether by hand or w/a hammer or by dropping it.) In the latter situation, the asbestos NOW becomes airborne!
ALso, this type of siding is not 'good' to just side over, EVEN if it's being first covered with, for example, 1/2" insulation board. When the NEW siding is being installed, what do you think is happening to the asbestos siding underneath??! It's getting smashed and it's crumbling, and you know what friable means now. And, besides, what probably 'looked' like a smooth, flat surface BEFORE the new siding went up, it now looks uneven because the old siding isn't 'in all the right places' any more!
So, long story short - Don't handle the siding, watch your kids, and if you're ever residing a home that has it, do remove it first. Broken pieces should be replaced.
Asbestos dangers in a home could be everywhere. Depending on the age of the house, it could be in the roofing, in the linoleum/floor tiles, in the siding, insulating the hot water pipes, in the wall insulation, and more. Here's a good start.