Req'd treated sill plate if I use Glulam seat ?

If you are using a glulam beam then it has been engineered. Check with the person (company) who engineered the beam for proper installation. Typically unless rated otherwise there does have to be some barrier between the beam and the concrete where ever they make contact for non-treated wood. You should be able to accomplish this with sill seal.

I actually sized the beam (it is way over-designed, but sized to match other conditions). I just wasn't sure about any building code issues regarding separation at the top of the concrete wall...

If it's not treated it needs to be separated. Same concept as setting a lvl beam in a pocket, you would put felt under it where it comes in contact with the concrete to create separation on the bottom and have a 1/2" air space around it.

Check with your local B.D. as they will be inspecting your work for safety and setbacks, use, lighting and ventilation, heating/cooling, wiring, etc. It will be listed on your home's personal record with the County so when you sell, your hard work will stay. Be safe, G