Gary, You should check more on this, but the kind of asbestos that is
dangerous is what's known as friable, the loose stuff like fiberglass
that they used to insulate heating pipes with. Also sawing any form of
asbestos is bad. I don't think that the asbestos in the tiles is a
particular danger. I would wear a mask and ventilate well, but it's not
haz mat stuff.
I dunno about sealing it, I would be tempted by an epoxy based coating.
someone will have more to say, no doubt.
Daisy