this is what it says at
www.wdwig.com regarding E-nights:
Can anyone purchase a ticket to Magic Kingdom E-Ride Nights ?
Disney Resort Guests, Hotel Plaza Blvd. Guests, Swan, Dolphin and Shades of Green Guests with multi-day passes can purchase a ticket for an after-hours party in the Magic Kingdom Park.
Offer good only for Disney Resort Guests with the following multi-day tickets: Ultimate Park Hopper, Park Hopper Plus, Park Hopper, Seasonal Pass, Annual Pass, Premium Annual Pass. You must have used your pass on the day of the event in order to gain entry.
that would suggest that E-Ride nights are available to Courtyard by Marriott guests, as it is on Hotel Plaza Blvd.
Regarding EMH - again from
www.wdwig.com:
On October 1, 2002, WDW began a new program for Disney Resort Guests (including guests of the Swan/Dolphin and the Hilton at Lake Buena Vista) called the "Extra Magic Hour".
this would suggest that you have to actually stay at a Disney resort, Swan, Dolphin, or Hilton LBV in order to take advantage of the extra magic hour - but more hotels will qualify for E-night, which the OP was concerned with
but i'm curious to know as well if i'm wrong!! thanks!