I don't have any experience with dry lotting sheep, but wouldn't want to try it with ewes.  Lambs are a different story, so maybe you could consider buying lambs and finishing them.

  One comment on feeding mineral, make CERTAIN it is SHEEP mineral.  Cattle mineral has too much copper in it and is fatal to sheep.  (So I'm told, don't want to find out)

Ewe's need to be checked at least every 4 hours during lambing, and 2-3 is better when possible.  When it comes to birthing problems, having Shepherd's hands is a must.  By that, I mean small hands.  My hands are not much bigger then most average sized females.  Better yet, remember that the best flocks are run by women, so get the wife ready to help.  Seriously, not a lot of room inside a ewe with one huge lamb or tangled trips, so small hands are a must.

Also, even lambs that are born without trouble still need to be put in a lambing jug for a couple days to get them to bond with the ewe or you will have a mess with no one knowing who mom is.

Someone mentioned having hoof trouble, and all I can tell you is buy clean sheep and be VERY careful about what you bring on the yard.  If you ever drag in hoof rot, you never forget the experience.  (Don't ask me how I know, but trust me, I know).