Dirt Devil Featherlite bag robustness & film on inside of front panel

 I was changing the vacuum bag of ye aulde Dirt Devil Featherlite
(bought about a decade ago) when I noticed that the bag had split
along one of the creases.  I usually pick up vacuum bags from a vacuum
accessories store (go figure) of which there aren't too many around my
parts of town.  I doubt the bag is made by the original Featherlite
manufacturer.

Have other Featherlite users found that such bags are prone to
breaking?  These are the "D" type/size bags.

I should add that live in such a small place with so little dirt
manufacturing activities that one bag can last many months.  I
wouldn't expect that degree of aging would affect the bags much, but
you never know.

Any experiences with age-related degradation of bags?

Finally, I noticed a very pronounced fine film of dust on the inside
of the plastic front cover that I remove to change the bage.  I
thought that the film was due to the split in the bag, and I washed it
away.  However, even with the new bag, a film develops very quickly.
The bag is fitted onto its nozzle all the way.

Is this pronounced film of dust on the inside of the front cover
"normal" in the sense that most people will find it in their
Featherlites?

I figure that it might be all the dust which is finer than what the
bag was meant to capture.  Kind of disturbing that such grime is being
spewed into the air we breath whenever we do cleaning, but that's a
different matter.  If everyone has it, there's no point beating myself
up trying to figure out where the leak is.