I did for my old 3rd edition covenant - one of the players made pretty pictures of what the tower looked like on the inside.
I don't think any of my current covenants have floor plans.
Depends. We have no map of Lumen Australis, our latest covenant. Some older covenants were mapped out in detail, down to the furniture in the rooms. Triamore has also been used and it is also maped. Right now I am starting to develop a covenant, and I will be using the manor house of Stokesay Castle ( en.wikipedia.org/wiki/Stokesay_Castle ) sans the gatehouse for the covenant buildings.
I was searching for something that would allow me to create maps like the ones in the Triamore covenant book. Would that be feasible with the se tools yo suggest? I perused them but did not find anything like that. More cartoonish. Or payment so didn't check.
You could also try Grid Cartographer. It's more for dungeon floorplans, and the full version costs money (the demo is quite limited), but it's quite cheap and really easy to use.