Lovely and sophisticated! I don't see anything that is glaring about the fit; it looks good but the pics aren't the best (I know how hard that can be esp. with black)
If you will be wearing black trousers, my mind goes to a black pointed toe, low vamp stiletto, like the one in the "find" but maybe that's too predictable? Do you need to stick to flats or block heels (for dancing or standing on lawns)? Would that be too dressy? You could also do a strappy sandal.
For a bag, I'd find a large, dressy clutch, maybe in patent or some kind of texture that contrasts with the lace, like maybe a metallic suede. If it were me, I'd stick to neutrals for accessories, but you'll have to judge that.
Jewelry depends on what you decide for you bag, IMO...if you go with metallic accessories then maybe do the same for the jewelry. If you go with something more solid for the accessories then maybe pearls - white or black - for the jewelry? It's sort of chicken/egg. I think find one item that is perfect - shoes or bag or jewelry - and then let the rest of the items work with it. My only guiding principle would be make sure you have a texture that works with the lace (no other lace items, for example) and I personally would stick to neutrals.
Now, let's see what Angie says!