You mention a lot of sample based instrument action here.
Have you tried the fixed version of the arpeggiator tool?
You can come a long way with that one. (And i’m currently finishing the RC that wil be posted on the official tools page)
Nevertheless a dynamic arpeggiator device that also supports audio streams including plugins would be very cool stuff. That is currently hard to do for tools (at least not much can be done as EA does currently).