The ceremony and reception will be near the State Game Lodge. The ceremony is at the Lovers Leap Deck and the reception will be at the Pavilion.
If you are staying overnight in the park you will need a park pass. If you are only in the park for the wedding mention the Gronewold/McLemore wedding at the gate for a free pass in
No. There are hotels in Rapid City and Custer which are about 20-30 minutes from ceremony and reception site.