Here you will find everything related to Linux on Surface RT
EFI booting is the recommended and easier way of booting linux. Advantages is support of all 2 GB. Disadvantage is worse performance because of L2 cache, CPU Idle and missing Dynamic voltage & frequency scaling (DVFS).
You will need an USB drive to boot Linux. (SD card; not strictly required)
Using APX mode to boot Linux is harder. But you have a decent performace boost with it. The features that make the performance boost are CPU Idle, L2 cache and Dynamic voltage & Frequency scaling (DVFS). Disadvantages is the missing 1 GB memory.
You will need a USB A-to-A cable and an SD card.
Screen (LVDS encoder, backlight)
SD Card (+UHS-I mode)
2 GB DDR3 RAM (only 1 GB for APX)
Vol+/-, PWR, Windows Buttons
Touch-/Type-/Powercover (EFI only) (+ hotplug detection,
suicide detector sensor hall effect lid sensor)
CPU temperatur sensors.
Some sensors (e.g. rotation sensor)