Ive been doing research on spacers and am only getting more confused!

Whats the difference between hub centric spacers and hub centric rings? I took a front rim off and didnt see any sort of spacer or shim but on the back wheel I can see a spacer between the rim and hub.

Also, when this shop first installed the rims the tech started to bring my car around front but stopped because the lug nuts they installed where a bit to long so they used a shorter set in (which they had also ordered for just this situation). I read that this sometimes can cause damage to the parking brake. Is there a way to check this out for myself? Im at the point where I dont trust this shop for much anymore but still have to have them install hub centric rings (on order) that they admitted not using in the first place. Do these rings make a standard spacer fit correctly?

Really sucks as Ive been wanting rims for years and now its turning out to be a crappy situation

Any help would be cool as I feel the next time i go in there its going to get heated