I have twelves ewes and five of last year's lambs, plus a wild ewe that was causing havoc and six wethers.
I did lose two ewes last year, presumably caught up in willow or something; otherwise they haven't caused me any problems.
I don't vaccinate them or give them any wormers, minerals, etc.; just two or three weeks of feed well before lambing - more to keep them tame than anything.
My plan is to cross two or three of them with my half milk sheep ram - for milking. Wonderful fleeces, but haven't got round to spinning yet - tho I did try out some felting.