'Sure' in an informal setting loosely translates to 'yes'. So if you reply, "yes" to my thank you, the meaning is a bit ambiguous. On the other hand, I've probably responded with "sure" to someone's thank you at least once in my life, but it's very casual and the sentiment can be misunderstood. Responding with "sure thing" is more appropriate and less ambiguous. You will see an example of this phrase used in response to a 'thank you' in the link below. https://www.macmillandictionary.com/us/dictionary/american/sure-thing

You can, but it is very informal and does depend on tone and what you say that ls for...This is quite specific and I obviously can't demonstrate. But as was said before- "sure, no problem" is fine. It is also less dependant on tone.

When I want to be informal and use "sure", I say "sure thing" or "sure, man/bro/dude". You could also say "sure, glad I could help".

"Sure" sounds dismissive, and maybe sarcastic as a single word. It is better to say "(It was ) my pleasure"or "I was happy I could help (you). Some say "no problem", but it lacks a genuine positive feeling. It is emotionless

It's okay if you say "Sure, no problem" or "Sure, any time" or even just "No problem"