Never post your content twice.
What this mean, that the users copy paste the same article and post it in 2 or more communities or in the article they've put 2-3 communities.

I mean if I do the Blogging Challenge I must publish my content in "blogging challenge" community - OK, but if my text is about "my favorite songs" can I add some community for Music as additional or this is not good (against the rules)?

Answer

By posting twice or more, it is meant to make multiple separate posts with the same or similar content. It is considered "milking the system" or cheating to get more rewards for the same content.
This is the bad way for "cross-posting"

In most Frontends you can find and option called "cross-post"

@PEAKD screenshot

@Ecency screenshot

Using this option, your post can be shared in multiple communities, every cross-post other than the original will have rewards option set to declined and it should stay that way. This is a safe way to cross-post, so if you really think that your post can bring value to more than one community it is OK to do it. But if you try to cheat the system to take more votes or rewards it should Not be OK to do it.

Does it answer it?

Question 2 from @projectmamabg

"Newbies Initiative - Goals for the Month and Basic Recommendations + Bonus Task" contest
I've already made my entry, but now after checking again, I think that I miss something to mention in it. In an article about styling the articles a user (sorry I don't remember who) said that when you make edits in your posts the people tagged in it will get the notification again. Is that true or it has been fixed somehow?

Answer

I just tested it in @ecency and mentioned users get notifications about edits. I think it is intended to work that way. A better UX approach will be a simple switch in advanced options that let you chose between sending notifications and not doing it.

Here is how a user see multiple edits of a post when he is mentioned in.

Question 3 from @projectmamabg

I've tried to promote a publication, I think that I did it because it took my points. Is there a place where I can see how many of my publications are promoted?

The way I know is going to you wallet in @eceny , from there click on** The ecency points** card/button
From there in the History section, you can find a drop down showing you the Outgoing transfers
Each of them is payment for boosing/promotion or a gilft to somebody.

I am expecting more questions.

I am open to corrections to my answers.

@projectmamabg
Your hash tag is too long, The longest and closest that can fit in the 24 symbol restriction
is #followforstrangequestion

Also if you think someone may need answers, send this post to him