How many wonders should be available on marktet? All of them or only four by age? We've played with all, but never can reach modern wonders with that setup. So maybe it must be like in core game. How do you think? How do you play?

Page 5 in the expansions rules, right column:

"Shuffle the modern wonders and deal 4 of them..." Same for medieval and ancient ones.

Hope it helps. :-)