Fey Changeling

Can this be summoned to an inhospitable location (e.g. underground) and die, but still have a chance to use its genesis ability first?

No. You cannot choose to summon a minion underground, underwater, or in the void unless it has the appropriate ability.

The term 'summon' means 'enter the realm.' So, does that mean I can play this minion for free?

No. This effect simply provides additional locations where you may summon this minion.