comparisons - What is the scope of "more" when making a list of comparatives?

Lets assume I have an object X of which I want to say (1) it's more important than Y and (2) it's smaller than Y (Y is left implicit in the examples.) If I say X is more important before saying X is smaller, would more extend it's meaning into small? In other words, which of the following two sentences is grammatically correct and also unambiguous, i.e, implies unequivocally that X has more of both attributes?

(1) X is more important and small. 
(2) X is more important and smaller.

Of course, the inverse it's easier: X is easier and more important.

Now, if both adjectives are more than two syllables long, is it necessary to use more twice?

(3) X is more important and expensive.
(4) X is more important and more expensive.

This same problem appears when making lists:

(5) X is more important, expensive and small.
(6) X is more important, more expensive and smaller.

Of the examples above,

• Which are grammatically correct?


• Which are unambiguous, i.e, mean that X has more of ALL the listed attributes and not simply more of the first and that it IS also the remaining ones? For instances, example 5 could be read as implying that X is more important, and that it's also expensive and small, but not more than Y for the last two.



• Does the scope of more extend to the whole list?