We have plenty of 40K mini's to utilize in our games. I also have a battlemap that is quared in inch blocks. Do I assume that each square is 1 meter for determining speed and distance? I looked in the rules and couldn't find anything conclusive.

That depends on the distance you want to cover in the combat. If you're in the cramped corridors of a ship or hive, 1 meter sounds about right. On the other hand side, more open terrain might lend itself to two metres per inch so the long-ranged weapons can play out their advantages as well.