Thanks for you effort ;) It's quite straight forward (from my point of view ;)
Casualties: See special rule "Growing numbers". You fight in melee, you win the melee, you apply the special rule "Growth(X)" to your unit where X is the number of wounds the opponent unit receives.
Max. units: See special rule "Growth(X)". Units can't get bigger than their unit size according to your army sheet. That's basically the unit size you would deploy your unit with in a standard OPR game.
Did you find the wording of special rules "Reinforcements" and "Fortify" easier to comprehend?
If you would try a game, I'm confident you would make it right!