Can I have some users on "Named" license, and other users on "Floating" license?

Yes, Accompa enables you to set up some of your users on "Named" license, and other users on "Floating" license.

On a related note: We recommend that your Admin users are always assigned a "Named" license. If you assign them a "Floating" license, it may prevent them from gaining access to the system to perform critical and/or urgent administrative tasks.