Ralph,
Both 'features' you describe are quite normal. The barrel can get quite hot and it is fairly typical.
The sight design is a bit of a design flaw, a very, very small spring that needs to keep a very, very small piece of metal in place during 9x19 recoil.... Whoever designed it must have had a rough night the day before
The slider part (small teeth) is usually worn down, causing a few of the teeth to be worn to such an extent that the sight can pop from 50 meters to 150 after one shot. The easiest 'fix' is to use a tie-wrap to keep it in place during shooting. Looks odd, but it works well.
The next level of course is shooting it with all bells and whistles: stock, (repro)holster and drum magazine. The holster, attached to the stock, will serve as an excellent and comfortable padding.