Because it has just those to grid systems, with all the bells and whistles of the versions that appeared around Jan. 20th, plus some more goodies.

Not sure we see the issue here Inger. The menu functions as designed. If you are talking about the faded menu icon behind the main icon that is a background that you can remove. It is not an issue, it is apart of the menu.

To remove it you would need to open the component, visit the Design pane and scroll down to the Background section. Then simply click the X next to the URL background. This will remove the image and 'fix' the menu as you say.

Not entirely. When the menu is inserted, it is showing just the two 'hamburgers'. When the viewport is widened, there are still just the two hamburgers. I need to click on them to see the menu items, also in wide. And they are visible until closed manually, regardless the viewport, the menu doesn't 'collapse' as e.g. the menu in Foundation.

Because this is a menu in Bootstrap, a totally different framework. As stated before it is how the menu was designed, it is a mobile menu at all times. If you do not wish the menu to function this way, you would need to choose the breakpoint in which you want the menu to unhide then from the Design pane visit the Position section and adjust the Display from None to Block on the Container element holding the menu items.

This would work just the same in Bootstrap as it does in Foundations. This is a component, something that we created, and is designed to function as is. You can use it as designed, or edit it to your liking. Just remember there is a difference between broken and as designed. I am sure as a Senior Advisor you can understand that.

You can view my edited menu here http://coffeecup-test.coffeecup.com/index.html which is more in line with what you are wanting.

To choose the collapse point of the menu for the set breakpoints you simply add the class "navbar-toggleable-xs" to the container with the class "collapse". To choose the next breakpoint up add the class "navbar-toggleable-sm" and so on.

That is the hard way, but Twin is correct. This is another way to accomplish the same thing.

Can we import *.rbb and *.rff projects into RSD 2.0?

Sure can! Just go to the File Menu > Open and you can select any project created with Foundation Framer and Bootstrap Builder.

Yes many websites now use just the hamburger symbol at ALL sizes to keep it out of the way of the rest of the page.
Many also have it as the ONLY method to toggle the menu On/OFF. This is for the light switch type user.
What I didn't like was the fact that at small screens they did not change the menu to a vertical type. This makes the menu not very handy without fixing this problem as the horizontal menu goes all crazy on multiple lines and looks poor.
This should have been put into the design of the component as done on websites with this type of menu layout.

Fantastic! I have created a number of RBB and RFF projects. I plan on testing them in RSD to see how they do here.