One eductor shows in the pics. I push water without them.
Another thread had a question about a mild winter situation and I got my knuckles rapped for not understanding "mild." For you I don't know if my experience is wicked enough, but here goes.
Yep, fill it. Freeze deep in the ground could crack or heave your shell, float it like a boat. The straight block walls may be a weak point for thick ice, but the sloped sides elsewhere would act to relieve lateral pressure if you get a non "mild" freeze. The Savio skimmer is a concern. Maybe you can treat it like a mini pool and put a mini air pillow in it to absorb expansion if it freezes hard.
If you're going to run it you need to finish up your plumbing connections for sure but were you planning a cover for the filter pit? A filter cabin with a glazed south wall? Bend some PVC and throw on visqueen as a minimum, you could have a mild three foot drift there in a week or two. Time spent now, before conducive weather is gone, building the cover you originally planned might be the best investmant of the little time you have left.
Landscaping and a fence!! Where are your priorities?
Mickey the windowman