The highest resolution will be 1080P, which is absolutely fantastic quality.
microSD. i believe they said they were limited to 8gb or less.
I finally settled for the Garmin Nuvi 275T. It was a close call between that and the 265Tm but the 275 model wins due to the advanced features and that it can be bought now for very close to $200. The touch screen, Bluetooth, text to speech and amazing satellite locking make it a fab unit. I highly recommend it.