How do I import layouts from other c2 project?

There's normaly no "automatic" way yet.
Open both project in a single instance of C2 (open programming first, then level design).
You can copy the objects to your recipient project. (let's say level design into programming)
Make sure you copy all objects from Level design's layout, have the correct names etc.
Then go in the event sheet of level design select the events (making sure all the objects required are created in the recipient project (audio, mouse, keyboard, sprites with correct names/instance variables, etc...)).
Copy them, paste them in the recipient event sheet.

Make sure that objects have different names in the project (so that you won't try to copy an instance of a sprite named Player with an instance variable "Health" onto a Sprite instance Player with an instance variable "Name" for example).
Local variables may need to be done in the recipient project manually, before copy/pasting events (a yellow tooltip should let you know about this "difference of variable scope", something like that).

It can be tedious (depending on the quantity of objects/events) but for now, this should be the road to take.

It depends on the setup of your project.
In the end, it might be easier to copy the events from programming into level design (considering sprites in programming are supposed to be placeholders whereas level design has the correct animation frames).
As said earlier, just make sure that the objects the events are refering to are already present in the destination project/layout.

I hope it helped.