This is far too fact dependent for anyone to be able to address here. I suggest that you consult with a lawyer in private and discuss it over...

Can artist protect his stage name even without having registered a trademark?

Just because the same was used as a title does not mean there is any trademark concerns. In fact, the title to single creative works are not...

Can I sale my Louis Vuitton purses? I think they are replicas.

No, you can get into hot water doing that.

Am I allowed to resell small brands like Guildon with my brand on it?

This depends on the context. For example, I'm free to go to a Vistaprint type provider and order promotional items like shirts or pens that have my...

Can I use a third-party name as part of my commercial software?

Sure, there is no issue with merely referencing these other entities. You are free to use another's trademark descriptively in text to refer to...

As noted, it really depends on the goods and services. It is not uncommon for mark holders to have to change their brand names in certain places...

How will I know if I were in trouble?

Sued for what? Copyright infringement? Not if you are using original or licensed artwork. Sued for trademark infringement? Not if you properly...

Do I have the right to perform a script at will that I wrote and obtained a copyright?

It sounds as if you acquired permission. Before you commit to anything, I suggest that you consult with a lawyer in private and discuss your...

Can i legally paraphrase notes from school textbooks in my school notebook without infringing copyright?

You're fine. When this is all for personal use not in any way connected to commercial activity and particularly so within the context of a...

After 3 consecutive years of nonuse there is a rebuttable argument that can be made that the mark has been abandoned. While you can certainly use...