Nope, especially when it comes to the more borderline things. It really depends on what variation you're using as a guide. For example, Whole 30 restricts honey as a sweetener, but many "regular" Paleo recipes are fine with it in moderation. Likewise, classical Cordain Paleo limits saturated fats and is okay with Canola oil, while Sisson's Primal recommends more fat, especially saturated, and favors coconut or olive oil over Canola.

That said, for the most part, you can handle a lot of foods with the "Paleo Flow chart" - http://ultimatepaleoguide.com/paleo-diet-flowchart-is-it-paleo/ I also like Bulletproof Exec's sliding scales for various foods, which is helpful when you can't just buy the "gold standard" stuff - http://www.bulletproofexec.com/the-complete-illustrated-one-page-bulletproof-diet/

For any other weird things, I'd probably look to the big names - Cordain, Kesser, Sisson, etc (or, if you're going more strict, like Whole 30 or AIP, then start with them and see if it's on their list of things to avoid) - and see if they've written anything about the particular item I'm looking for information about. Sisson has an entire series on "Is it Primal?" where he looks at particular foods and discusses whether it falls in line with Primal principles or not. Read the information and see if it might work for you. Then try it and see whether it has any adverse effects.

The thing to always remember is that Paleo is not an arbitrary list of foods that you should or shouldn't eat, but a whole foods framework in which to make your own decisions based on the science available. Even the things that general Paleo does explicitly say to avoid, it does so because there has been a ton of research that says "these things in these foods are very, very bad for you and are likely causing most, if not all, of your ills."

Also, if you're still unsure, and/or you can't find the information you're looking for, feel free to ask here. If you're asking, it's a pretty safe bet that someone else has already asked at some point or another.

Nope. Take what's useful for you and leave the rest. I have my own set of criteria and others have their own. For me, I think it's important to not only limit processed foods but also boycott the big name brands as much as possible. So, that limits me even more than some other people choose.

It's easy to look at a food and determine if it's acceptable. If you buy foods with an ingredient list, read it, learn what all the stuff is (Google is your friend) and how the industry gets away with sneaky additives, for instance "natural flavours" and stuff like that.