you can tell thier entry point by looking at the minimap and seeing a box with thier color on it

woods, it depends on what kind of troops you have I used calvary before with success

I have never rested my troops back to fresh but have gotten back to from exausted to winded I think the timer would run out if you rested them that long

in big battles try to outflank the enemy rather than slug it out use your infantry to keep or hold the enemies units in place then use your calvary to charge into the sides or rear , this will usually cause a route when enough units do this it will start a chain reaction and cause the entire army to route if the battle ends and it asks if you want to continue the battle(in the case of big armies) definetly do it if you dont wipe thier army out you will probably see it again next season besieging one of your towns or something