We would like to update a Custom Field (Last Activity Date) on the Accounts Object from many different places. The idea was to use a Flow (no Apex Coder on staff) to update the custom field on Account whenever one of theses things are created/updated: Notes, Activites, Opportunities, Contacts, or Orders. The problem is Notes and Activities. In Flow, neither are options in the "Select Object". Notes and Activities are use a lot in our Org. 
Again, the goal is get a better full vision view of what is happening with an Account down to one field so we can report off that in the future. Does anyone have any suggestions?

We use the Orders Object to track and report our Sales in SF. I am looking for a report to gather the LAST 365 days of Sales for an account and then sum it up to the Account Owner. From there, I want to compare that to the previous 365 days (so day 366 to day 730). Then see the percent different between those 2 numbers. I have tried using the PREVGROUPVAL function, but that seems to only work on Opportunities, but we are not using Opportunities. Please help me find another solution

We would like to update a Custom Field (Last Activity Date) on the Accounts Object from many different places. The idea was to use a Flow (no Apex Coder on staff) to update the custom field on Account whenever one of theses things are created/updated: Notes, Activites, Opportunities, Contacts, or Orders. The problem is Notes and Activities. In Flow, neither are options in the "Select Object". Notes and Activities are use a lot in our Org. 
Again, the goal is get a better full vision view of what is happening with an Account down to one field so we can report off that in the future. Does anyone have any suggestions?

We use the Orders Object to track and report our Sales in SF. I am looking for a report to gather the LAST 365 days of Sales for an account and then sum it up to the Account Owner. From there, I want to compare that to the previous 365 days (so day 366 to day 730). Then see the percent different between those 2 numbers. I have tried using the PREVGROUPVAL function, but that seems to only work on Opportunities, but we are not using Opportunities. Please help me find another solution