Glad you like the game. I think it's amazing. That being said, Sand Storm king making makes me super salty.
1) No, exhausting units for combat is an ability and can be used before or after declaring combat. This is important because a card might be discarded as a casualty before it has a chance to contribute. That being said, it's occasionally smart to forfeit units before battle in case you hit a Minefield.
2) Only Supply cards can be played from your hand after combat has been declared.
3) Yes, removing Box Positions is an ability and can be used before or after declaring combat.
nice! Biggest thing we found thats different, its WAY harder to get money in El Alamein. nobody ever got the money for the 7 cost tanks.
Granted it was our first game, I want wait to add in Barbarossas cards, the ones that let you upgrade your money cards.
so hyped... love the game tho