Help with creating a pattern (hook size + mirroring)

I’m currently writing a pattern, but for hook sizes 1.00 and 0.7.

Can it simply be crocheted with a different hook, e.g. 2.5?

Or would it be better to rewrite the whole pattern for size 2.5?

Since I always struggle with mirroring, can I just crochet the pieces twice on the right side and then turn one of them to the wrong side, even if the pattern is only on one side?

If you crochet with a larger hook, the piece will be bigger.
If you crochet in the round, the pattern on the left side will be different from the right side. If you crochet in rows, both sides will look the same—at least if you crochet all the same stitches. 
 

Well, I always test my designs with different hook sizes if I want to offer them as “crochetable with any hook size.” My test crocheters then test it again with different hook sizes.
You just have to try it out for yourself, because different hook sizes can also cause a crocheted item made with thick yarn to look different than one made with thin yarn—not just bigger, but possibly also more contracted or stretched out. Of course, it also depends on the item. I only crochet decorative items, not clothing.
As for the right and wrong sides: If you have a certain pattern on one side, it might look completely different on the back. But you’d have to see that for yourself when you crochet it. Or am I misunderstanding your question?

It’s not about a specific pattern—it’s just about decreases and increases, and that works at least for rows. I just tried it out.