Re: [Nutaku] Kamihime Project R
No clue about Alyssa. Gold gatcha posted rates of 3% SSR, 15% SR, and 82% R.
From the gold gatcha odds (which list contents), there are:
23 SSR weapons (Gold gatcha lists 7 SSR himes as rewards, there may be more hime that are unlisted)
40 SR weapons (Gold gatcha lists 7 SR himes as rewards, there may be more hime that are unlisted)
~82 R weapons (9 pages, 8/page +1 holdover, )
12 SSR Eidolon
26 SR Eidolon
~34 R Eidolon (4 page, 8/page + 2 holdover)
. . . Yes, I counted. If the Magic Jewel Gatcha mimics the Gold gatcha, this should give you an idea.
As for SSR events in the future, there will be some as the Misson screen and Shop screen (materials exchange section) have an events tab. No idea how often they'll be run though, but Nutaku does like their monthly events.