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?

Generally, I would not use "more" in a way that extended its effect beyond the one following adjective.

An important exception to that would be where two or more adjectives were being used as part of an idiomatic set phrase, or to convey a single impression e.g:

"more tattered and torn", "more rough and ready", "more rich and powerful", "more decent and honest", "more cheap and cheerful" etc