I suggest using Androidplot for dynamic data. Full disclosure: I'm the primary developer of Androidplot so I'm a little biased but I'll try to defend my suggestion:
One of Androidplot's core focuses is the accurate representation of dynamic data, whereas other libraries seems to focus on either static data or for lack of a better term semi-dynamic data. It's possible to animate plots from other plotting libraries to get a "dynamic" display but there is high potential for race conditions between the data model and the display data, especially in the scenario you mention above where the model is updated at a much higher frequency than the display.
There are also issues with plotting large amounts of data, or even small amounts of data at high frequency using the main thread. This can impact the UX by adding latency to UI interactions and even potentially occupying the main thread long enough for the OS to assume the application has hung. Androidplot solves this problem by providing the option to do all rendering in a background thread, keeping the main thread free of delays. This is a feature (rendering from a background thread) that (as far as I am currently aware) is unique only to Androidplot.
I won't say Androidplot is the end-all-be-all charting library for Android and certainly there are several other good libraries, but your particular requirements especially fit one of the primary use cases for which Androidplot was designed.
/sales pitch over :)
EDIT: As far as scrolling / zooming of dynamic data: It's as easy as using the XYPlotZoomPan class instead of XYPlot :-)