I've experienced this once too, against a minotaur. Really annoying.
Verity_
This should definitely be in. Much better than having people quitting, it's really boring finishing against ai.
This should be fixed. Why would you ever want to stop after casting a spell, especially after a wand of speed?
I like all of your ideas. I seriously don't see why you shouldn't be allowed to queue up commands, it would make it much easier tocommand your minions. To be able to set them out on a route to destroy specific buildings or units would be really useful I think.
I think it's a fun tactic. You just need to stay alert if you have lost the center and be ready to teleport back if they try to steal it. But perhaps some extra towers at the portal would be a good idea anyway, it should never be too easy to steal a portal.
Sweet update :) The new map is really cool and with the new game optiosn you can get some really epic battles :D