The short answer to both of these questions is a big NO! When you buy PLR you are buying a license to use the content as you wish. Licenses vary a bit from provider to provider, but generally you get the right to edit the content (or not) and publish it under your own name. You have paid for the right to use the content, so it is not stealing and there is nothing unethical about it.
I’ve had people say that they don’t want to use PLR because they are afraid their customers will see the same content on another site and think they stole it. That is unlikely. Even if a lot of people buy the same PLR package, most of them will never use it (sad but true).
The smart ones will customize the content. As you are one of the smart ones, that is what you will do. That means that even if someone runs across another site that has content based on the same PLR they probably won’t recognize it. Keep in mind, too, that even if someone read the exact same article weeks or months ago, they are probably not going to remember it.
Still not convinced that it is okay to use content you didn’t write? Walk in to a bookstore and pick up an autobiography of a famous entertainer, sports figure or politician. Chances are they didn’t write the book themselves. Read the acknowledgements and they will often thank the actual writer although they may not admit that the reason “this book would not have been possible without them” is because that person actually wrote it. Basketball superstar Charles Barkley famously complained that he was misquoted in his autobiography, so clearly he didn’t write it!
If you feel uncomfortable putting your name on content you didn’t write, there are a few ways around it. First of all, if you added your own ideas and voice to the content, it is yours. Don’t feel guilty about using the shortcut of PLR to get it started. However, if you are using something with minimal changes you could say the content is “presented by” you. Or you could put a pseudonym on the content and offer it as a guest post. (One note about using a pen name on PLR: Most PLR providers do not want you to put their name on the content when you publish it, so don’t do that.)
I have several ghostwritten articles (not PLR) on one of my sites that I credit to a phantom staff writer. Of course, as long as have licensed the content, you can put your name on it and hold your head high.