2017-04-18 : Desert is a land subtype with no special meaning. It doesn’t grant the land an intrinsic mana ability. Other cards may care about which lands are Deserts.

2017-07-14 : To activate the last ability, you may tap any untapped creature you control, including one you haven’t controlled continuously since the beginning of your most recent turn. (Note that tapping the creature doesn’t use {T} [the tap symbol].)