
Hi @FishyFish,
Could you please show a bit more about the DEP policy? Is it the Data Execution Prevention policy?
For your first question, if the DEP policy that you mentioned is the Data Execution Prevention policy, I think it is not necessary for all users to own Flow 2 plan to apply DEP policy. The DEP (Data Execution Prevention) policy is a system-level memory protection feature available in Windows operating systems. In other words, this policy is based on operating system. More details about the Data Execution Prevention policy, please check the following article:
For your second question, not all users need a Flow Plan 2 license to update flows, the Flow Plan 1 license and Microsoft Flow for Office 365 license both support updating flows. More details about the licenses of Microsoft Flow, please check the following article:
https://preview.flow.microsoft.com/en-us/pricing/
For your third question, the PowerApps Plan 1 license includes Flow Plan 1 license rather than Flow Plan 2 license. More details about the licenses of PowerApps, please check the following article:
https://powerapps.microsoft.com/en-us/pricing/
Best regards,
Kris