IDK about the heater but we use the autostart on my wife'* 08 SRX all the time in the summer and I know the AC turns on and cools the cabin down before we get into the car. Im sure it the same when its cold out side I think you just need to leave the temp control set to auto. I would read the owners manual to make sure.
if you have auto it will heat in the winter and cool in the summer. i wish i could turn mine off because it just blasts what ever because the engine isnt warm or the a/c hasent been on long so its pointless