I shot an event with the Tammy 28-75 f 2,8 and the Kx..had a 50-200 and the kit 18-55 too for long shots and wide ones...the place was pretty crowded but the 28-75 never left my camera..and i'm very satisfied (as was the client) with the shots....
The primes are really nice and the 31mm is a FL you will certainly use a lot...but the Tammy will offer you more versatility and it's price is hard to beat.
With 1000 you can buy the Tammy new and you can assemble a nice portable flash setup for 350-400 more (a pair of YN560, remote flash triggers, diffusers and reflectors and cheap light tripods...). Or you can buy the 70-200 f 2,8 for candids and for the ceremony, spending a bit more...being interiors you will have to shoot raw and iso 800-1600-3200 depending on the place.
If you have someone to help you, setting a place where you can photograph the people, like those in the big events with celebrities, can be a good idea.
In any case have luck (and don't worry the Kx is very able and i'm sure you will succeed
).