Crutis
Try using the [G]roup command. The computer will then remember the formation and you can drag your entire army formation onto a new location. There are bugs in version 1.0/1.1 but they are fixed 1.2 *crossesfingers*.

Your best bet to hold chariots with Romans Auxilia Spears is to make deep formations, 6+, and place your units side by side. The chariots will bash through, but they will lose eventually. I did 2 tests with 3 Heavy Chariots + 3 British Warlords versus 8 Auxilias and the latter only lost 15 or so soldiers per unit.