1.The topbolt going into the starnut get's tightened first.That sets the pressure on the bearings.Tight enough not to have play in your headset,but not so tight that it binds.Then you tighten the stembolts.
2.A little gap between the faceplate and stem is normal.From the pictures it looks like the clamparea on your handlebars is kinda worn down.I had a similar problem with old flop n' chops(that's what your bars are,right?).Once the knurling is worn down it's hard to get the bars to stay put.