Belgium Stamp Cancellation Identification Help Needed

I have several stamps in my Belgium collection that I could use a little help with. There are six images.



1) judging by the paper remaining on the backs of these stamps I think they are from the same piece. The cancellation is what intrigues me. Is this a special cancellation of some sort?



2) this stamp has what looks like a hole punch. Any ideas on what that might be other than an accidental hole punch?



3) my assumption here is that this is a postage due stamp circa 1960



4) this one really has me stumped. The stamp on the right is the proper olive grey colour. The stamp on the left is a blue grey colour and I can find no reference for the variety. Any ideas?



5) this seems to be cut from a postal stationery card circa 1905. A catalogue reference number would be appreciated.



6) I have several stamps with this fancy cancellation. Is it a pre-cancel type or something else?

Thanks for any help.

Hopefully someone will be able to answer all your questions, but stamp #6 has a roller cancel. These are normally valued much less than regular style postmarks.

No. 6 is a precancel used only for financial documents sent out from the Caisse d'Epargne, which was a kind of savings bank.

Your cancellation with the plane is from a slogan cancellation.

Here is an image of the complete cancel.

Chimo

Bujutsu

Bujutsu's cancel reads: "Use Air Mail" in both French and Dutch.

Peter