do the yellow arrows and the blue pop up screens work in multiplayer for battlefront 2 ???

The yellow objective marker arrows should.

I would be surprised if the popup screens did work though, since they pause the game in the background until you click out of them, and that would not go smoothly in multiplayer when each person has to individually click out of their own popup. I could be wrong though.

cool thanks

Popup screens do not work in multiplayer.

Me and a few friends are trying to make the Rise of the Empire levels more multiplayer friendly by removing crashes,bugs, etc.

One of the things we had to remove was every instance of popupText.
We found this to do two main things:

1) Players cannot jump or fly.
2) Players cannot enter vehicles.

This is because popupText screens count as visual information, and in the swbf game engine, the player controls any visuals.

Host cannot control player visuals, and it is trying to send something that the client cannot receive.
This is why I could play online with a yellow Wookiee if I wanted to, and you will have the default Wookiee skin.

The host sends popupText and thinks the player has paused which prevents tank entrance and jumping.
The player how ever has not actually gotten the popupText screen.

Lastly, popup screens work fine for the host, because the host is not relying on another host.

An alternative would be some long messages ran on the game using ShowMessageText.

Edit:
When you press M to look at the minimap, you would notice some yellow text, usually objective information. I've known this not to work online either but I am not completely sure.