This one of those problems where you have to work backwards, right? Haven't done one of these in a while.
You know how much copper two carbonate you made, so you should be able to find out how much copper ion and CO3 were there to react to make that amount. You might aso be able to figure out how much CO3 reacted with the water from the second equation. Honestly I can't figure this out right now... Just closely inspect the order of reactions and the whole process and you'll see it.
But the powder versus solid, powder has more surface area and will react faster than a solid. So if the reaction runs it will be slower.
If the sodium decahydrate were relieved of it's hydrate component, it would interfere with the second reaction by adding products to the equation, shifting the equilibrium to the left. So it would be less favorable for that reaction to proceed. I haven't really learned about hydrate chemistry so that may be wrong. Maybe the H will react with the hydrate instead of the CO3?
Also vacuum filtration is annoying with powders if you're trying to get a high percent yield of a small amount of stuff.