VEVOR Geotextile Fabric, 12.5 x 50 ft 3.5oz Woven PP Driveway Drain Cloth with 600lbs Tensile Strength, Heavy Duty Underlayment for Soil Stabilization, Landscaping, Weed Barrier, 12.5FT50FT-3.5OZ, Bla

I don't see the point in this but yes you can and I highly recommend wire mesh reinforcement at least.

Not sure why you'd want to pour concrete over this? It is for weed control and allows moisture to get into the soil and helps stabilize the soil some.

I don’t see why not. Not much different than poring over a plastic sheet moisture barrier except don’t expect it to act like a moisture barrier

This is giving the weight as amount of material to expect per square metre/yard. It's basically a measure of effectiveness. A heavier material may filter better, or slow down liquid flow. You'd have to look up and compare performance per particulars. The item appears to be groundcloth over the drainage around the base of a foundation,in which case it would prevent perforated pipe from being clogged by sand and silt.

8oz is per square yard (3ft X 3ft) And 226.8g is per square meter. Same values, just different units (oz vs grams; yard vs meter)