You've got two examples there.
The first (dual licensed software and distribution) is something that can fall in the scope of Programmers.SE. Note that if the question gets too deep into the legal aspects of the licenses that go beyond what a programmer can give an expert answer to it tends to get marked as off topic and you need to go talk to a lawyer.
The second (third party license interpretation) is one that rapidly falls into the realm of 'ask a lawyer' and tends to be off topic on all sites. Programmers have no insight into if ${arbitrary tool} can be used for ${purpose} according to ${3rd party license}. Visual Studio is one that programmers may be able to give information about, but not Photoshop, or logo designer, or random game engine, etc...
Recently (April 16th, 2014) closed on Area 51 was Open Source Licensing that would have been a good place to ask the first if it had ever gone live. Reading the question Did you know licensing questions are explicitly on-topic at Programmers SE? can give you some insight into how P.SE could be a good place to ask.
I should also point several key words in your question:
Is there a stackexchange website where you can discuss software, app licenses. What is possible what not. What is legal what not.
discuss - discussions are not a good fit for the Stack Exchange Q&A format. If you wish to discuss something, consider going to an appropriate chat room and asking it there. Stack Exchange's format does not mesh well with forum style discussions.
legal - Questions about what is legal or not are things that need to be asked of lawyers, not random people on the internet. We cannot account properly for your jurisdiction or nuances of your situation to be able to properly answer it even if we were experts in matters of law.