Ving,
I think the burn up question could be answered by considering the mass/inertia of the system. Dust sized particles entering the extremities of our atmosphere would loose velocity in short order. Without inertia to mess around with acceleration (negative in this case), and without a large thermal mass to retain heat energy, it could well be that there would be minimal heating up of the dust particles.
Ric,
I've been waiting years for few 20kg Snapper to drop out of the sky next to my BBQ, but nothing yet, not even a mud gudgeon
Cheers,
Doug