It would be beter to educate then ban outright IMO. If you ban the device outright kids will be sneaky about it. When I was still in school we hat smartphones and used it from time to time. Great tool for meeting with friends from other classes. Sending a message to your parents you can leave early or something. Outright banning phones is IMO stupid and only makes the problem worse. We should teach kids to be responsible instead.

To get too know the true spec you need special measuring devices. No software can tell you the true spec without knowing the actual inside of the cable. You can do a few test to get a rough estimate though. But that means testing all the capabilities and see what it does. Could be using the cables way out of spec that way however.