Question about knob and tube and fmc with fiber insulation

I looked at a house recently with some knob and tube and fmc without a ground wire with fiber insulation.

Can someone tell me the age range of the fmc? I can only assume it is newer than the knob and tube. How unsafe is the era considered? Obviously the lack of a ground but is there an additional risk of the fiber breaking down with age?

The knob and tube led up from the basement into the wall cavity. Was this stuff typically run with the same pattern of extra jacketing through framing and knobs at intervals to support the wire? Does it always have some fiber insulation or is it ever just raw wire?

Thanks for the education.