im sure its fine to leave the esc where it is as long as the area doesnt heat up from the lipo. you definitly shouldnt discahrge your lipo. in fact charge it up again to full before you fly. you really never need to discharge lipos. they dont have "memory" like older nmh or ni cad batteries. if you run your plane for 1 minute and then charge it again it will do no damage to the battery. Also if you discahrge a lipo too far it will be permanty damaged so make sure if you do discharge your battery for some reason not to let the voltage get to low. hope this helps
-alex