signs?

Yes it's this !

does it matter, where the car should cross the gap? i mean only in the middle or in the end / in the beginning is ok?

It does not matter at all, because the gap is uniform at every points anyway

i mean where it should cross the row of the gaps ? still doesnt matter?

I don't really understand what you mean.
There is one gap and you have to cross it twice. It doesn't matter in which places you cross it

kinda forces to make a flowless map gonna give it a try tho.

what about water? can I put it anywhere as terraforming or not?

do we have to fill the complete width of 5 blocks? or would it be okay doing it like 2*32?

AR »DrHugs. says:
kinda forces to make a flowless map gonna give it a try tho.

You misspelled flawless, DrHugs
Well, the MTCs are supposed to be a challenge and bring new ideas into mapping. It's all about playing around and having fun in the editor. I am very sure that a flowy map is possible to build even in such a restriced building area. But it would be nice to see it proven by an example.

water = terraforming. All blocks you can drag/place in the f1 menu are terraforming.

How are you supposed to fill the entire building area? Not even D75 can do this. Only fill as much as you want