I can't see an option to be able to select a plunge point for 2d or 3d truemill operations.. and you normally do a helical entrance, so using the default point it selects shouldn't be a problem..
as for having multiple tools in one 2d truemill operation, that wont work.. but you can do that in a 3d truemill operation..
now, you could do your 2d truemill operation, then do a rest material operation to clean out the areas where your truemill tool didn't hit.
Just when you thought you had it all figured out, all hell breaks loose..