One frequent issue I have with this mod is determining whether my power is being over utilized by changes to my factory.

These changes are usually made within the last minute and due to the power interface provided by factorio not graphing total production/consumption, it is very difficult to read power utilization using the instantaneous bars on the power menu (left clicking on a power pole). This is largely caused due to the very short work intervals (which are a major feature of this mod).

Is there a way to open a second small menu for utilization over the past minute? It's a quality of life addition. If not, are there any mods which would give me a more powerful visualization tool to monitor my total power and usage over time?

This is a problem of the 0.14 version. It's not supported anymore and never worked flawlessly. If you have problems with ups I highly recommend updating to 0.15 experimental that runs very stable and improves performance of the game significantly, than using the newest version of ups up that deos not support Intervall stuff anymore, because it's no longer needed. About your problem I don't know a fix for this unfortunally.