Eugene, you can not exatly align it but to get it better aligned you may:
- set maximum and minimum scale in Value Scale identical
- uncheck the Dataset Name, Last Value and Units in Trend Properties
to your 2nd question - I can only assume that your XY plot is to small to show the scale, because it works in my case. If your trend is to small, PI Webparts decide what can be displayed and what not, AFAIK there is no way to control this other than making your XY plot bigger.