echarry,
1) The First Call?.vi is a function used to control boolean logic. This returns a true value as soon as the VI starts to run. This could be wired to subVIs or structures to cause other events to happen. It is not explicitly need for data flow though as coding logic will still take precedence (the code is read left to right).
2) Waveform charts are great for "real-time" aquisition and viewing. This is because the chart as an internal FIFO that stores the points as they come in and connects the lines, building your graph as you go along. A waveform graph "reinitializes" everytime, meaning that the data sitting at the door gets reread in it's entirety every iteration. Since you are wanting to see your filtered data as it comes in, it sounds like you need to filter it point by point and pass that into the waveform chart.
3) I don't know for sure whether you need queues or not for your application. My best recommendation is to try both and if you are happy with the results without them then dont use them.
Hope this info was helpful. Good Luck!!
