Advanced building???

At WC2 and SC/BW there is this secondary building thing form workers... Can you do that in WC3?

Not really.

Some people have an ability button for their worker that replaces them with a different unit that can build different buildings.

It's very much possible, at least for undead. By using a modified spellbook spell as the advanced structures button and modifying the 'Tiny Great Hall' type item abilities to create the structures you want, you can have acolytes with two pages of buildings.

The problem with other races is that they won't actually stand around building, but since undead buildings are summoned anyway, that's not an issue for acolytes.

You could probably make others look and act like they're building using triggers, though.

There is actually a button they made for the humans that is "advanced structure", I'm guessing they were planning on doing that and then decided against it.

If you need an advanced buiding ability, I've put one for download (trigger enhanced spells section). Though it might not be the best solution to the problem and it has some limitations, it works good for my single player campaign.