Thanks for getting in touch!
1) You can add text to an SChartAnnotation and place it using data values as coordinates for where you want the text to be placed. The SChartAnnotation method you require can be found HERE.
2) This is a known issue with our charts and a work around solution would be to increase the maximum value of your range to a value slightly higher than 50 so the label doesn't get clipped.
3) This isn't an issue we are aware of. Is there any chance you could manipulate one of our sample apps to reproduce this issue and send it in to us at firstname.lastname@example.org?
This would really help us identify the source of your issue.