Question

Instead say, It is a +adjective + object= C'est un _________ impermeable, for example.

Answer 1

C'est un bel imperméable.
C'est une vieille télé.
C'est une vieille voiture.
Ce sont de belles feuilles.
C'est un bel homme.
C'est une robe neuve.
C'est un vieux papier.
C'est une belle chemise.

Answer 2

This structure doesn't work for everything on the attachment. For example,
Question #5 would not be:

"C'est un garçon bel", as that is not simply how one writes it. Instead, the adjective precedes the object, making:
"C'est un bel garçon."

Another example, #7, "C'est un vieux journal."

I don't think it's "C'est un journal vieux...", from what I've learnt.

I don't exactly think there is a definite rule on what types of adjectives go before or after (I think most go after), but personally, I have learnt a some sort of rule from my teacher (by this, I mean that the rule has exceptions) whereby the adjectives that come before the object are encapsulated by this acronym, BANGS, meaning:
Beauty – e.g. beau, belle, moche, etc.
Age – j'ai dix ans (not a c'est + adj + obj structure though)
Number – ils ont deux chiens.
Goodness – bon, bonne, mauvais, mauvaise, etc.
Size – grand, grande, petit, petite, etc.

Hope this helps :D