I'm new to SWAT 4 and can't find out how you are able to program a plan and execute it. To be more specific I'm looking for go codes. How do I perform such thing?

This is not possible in the base game.

If you launch the the expansion, Stechkov Syndicate, it is one of the features added by he expansion. The expansion's main menu has a menu item called New Feature that explains how to use it.

It very simple and only allows you to plan a simple entrence like a simultanous breach of a room
The default key, is ctrl which will have the command wait in the queue before you order initiate. It works with any command. Back to the simultanous breach example, while holding control, issue the order to red to open and clear, then walk with blue team to the other door and while holding control order the blue to open and clear. Finally to get both teams to act in unison, order gold to initiate.

A SWAT game without go codes (FACEPALM and LOL). Is there a way to play the base campaign in the expansion? Or does a mod exist which implements this feature into the base game?

I personally play with the Elite Force mod which even merges the two campaign together with some new content. Elite force does change a few game mechanics however.

Ok but are the initiate commands present in the base campaign while using the Elite force mod?

Elite force doesn't have a stand alone base campaign or stand alone expansion campaign anymore.

The missions for both are in a merged campaign and and the commands can be used in all the missions along with all the new equipment and features.

OK thanks that's what I wanted to know. I've got another question if you don't mind. What's the difference between these green en orange colored threads? Are orange ones for questions only? And how do you select those when creating a thread?

Oh and what is the latest version of the elite force mod? Is that 6.4? I see people comment on v7 but has that been released yet?