Hi 

I put it on our development road map. Unfortunately in March all our development slots are filled, so this enhancement will be available on production in the second week of April. 

It seems useful and interesting. We have to think how to this from UX perspective.

I keep this issue opened to allow other users to comment.

It is hard to imagine that you can set reasonable default values for data type/length/null of column for the whole model where you usually have hundreds or thousands columns with different types/length etc. So we don't plan to implement such feature.

Regarding column name patter it duplicates the following issue:
http://support.vertabelo.com/topic/565476-pattern-for-naming-objects/
You can vote up.

Ad. 1 It is on the way. We plan it to have on production in February.
Ad. 2 Interesting improvement. We will add it do our roadmap of UI/UX enhancement.
Ad. 3 To be considered. The little problem is that it can conflict with popping up column type selector (Enter key). We will analyze it.

We consider to add such possibility. So I keep the issue open for comment and vote by other users.

I guess that you mean about results you get after click on "Preview SQL" button. 

We don't show foreign keys because it is a part of different diagram element - Reference. This behaviour is intentional.  

Subject areas and possibility of changing colors of diagrams elements are the only elements designated to manage visual side of the model.

The color of model area is a part of the whole Vertabelo visual design and it has to correspond to others elements - panels, controls, grid etc.. So we don't plan to add user possibility of changing it (however it is very simple from implementation point of view).