Yes, both of the hotels listed are on Saint Mary's Campus and a short walk to the ceremony in Le Mans. There will be signs on campus and maps in the hotels. There is also parking close to the ceremony and reception and you are more than welcome to drop people off at the doors of Le Mans (where Holy Spirit Chapel is).
Yes, the cocktail hour and reception are on the greens right in front of Le Mans. There will be people directing you from the ceremony to the cocktail hour and there will be signs on campus.
Weather pending, yes. The Cocktail Hour is open air and the Reception is tented. Both are on grass so please wear shoes fit for walking outside, (and for dancing :).