Question about game's mechanics

[RVPERTVS]

Thank's a lot guys..very useful advice, but I got some other questions regarding the info given in your replies:

1.- What exactly is the effect of "stumbled upon" attack?

2.- What is reverse slope defence?

So far I have more or less neglected the use of infantry because I'm playing open desert maps where tanks usually get the job done with some helo recon, but I know that this game is focused on "the queen of battle", so

3.- What's the best use of infantry in open desert maps?, and

4.- What's the best tactic to get the infantry to lead my armor in open desert maps if infantry has a lower speed range?...APC's?..mounting and dismounting?is there another way?

Thank's in advance