You are looking to do content curation.
Not everyone likes their content to be hotlinked. Be courteous and ask. Also, not everyone wants their content just copied over, and you certainly, at the barest minimum, give credit and a link back. But, you see, if your Google Page Rank is lower than theirs is, you're not helping them with SEO. And anyone savvy in that area isn't going to be too pleased with your link back.
So the answers to #1, #2 and #3 are - ask the site owner(s) and see what they say.
#4 I write newsletters and all sorts of stuff online, all the time. How do I do it? I have topics and I create content for them. So brainstorm some topics - way, way more than you think you will ever need - before you even start this.
Oh, and one more thing, particularly with reference to your first three questions - can you just steal other people's works? I'm not saying it's difficult. In some areas, it's pretty damned easy. But it's not right. So obey Wheaton's Law -