Check this site out. They may give you some ideas of what to look for. But I would think that a small yorkie would get thru the slats. I use an xpenbecause it has small enough openings that puppies cannot get thru.. Yes if you leave it straight it will fall over. You need to make it stable by angleing each section a little and it will be very stable and cover a large area. I bought 2 complete sets ( total of 12 panels) and attached them to make a large area in my family room for them.
http://www.bargainpetstuff.com/Gates.htm