Are these sentences OK?
How many of them did you buy?
How many did you buy for me?
How much did you buy those things for?
The dreams don't know of boundaries.
What a kind behavior you just did.

Question

Are these sentences OK?
How many of them did you buy?
How many did you buy for me? 
How much did you buy those things for?
The dreams don't know of boundaries.
What a kind behavior you just did.

Answer

1. correct
2. correct
3. correct
4. Dreams know no boundaries.
5. What a kind gesture you just displayed.