As Fighter said, you can do both of these.
In Max, when you create your material you’ll need to select a Multi/sub object for the material type. Once you do this there will be multiple slots that come up (10 by default). you can set the number to whatever you like, but only the ones used on the mesh in question will be included with the export. (ie. if you setup 5 materials but only use 3 on your mesh it will only export those 3)
On your mesh where the material is applied you’ll want to select your polygons you want to have that material ID and set it appropriately.
I didn’t watch this all the way through but I did skim and the process is correct for setting up Multi/sub object materials. If you have any questions feel free to ask. I use them extensively in my personal projects and in general.