first question: Should I approach a publisher/editor/professional book-person first, saying: Hey, I have this idea, I have this timeline, I want to do X or Y... OR should I rather start, finish a draft, have a written manuscript, then go around and see if someone pays interest?
Both are valid options, depending on what exactly you're doing. What are your expectations? I'm a professional editor. If I were willing to give you my name and if you were to do a search for it on amazon, you would find books that I have edited. So, here I am. Approach me. What do you want to know?
What are your goals? Do you want to write a book or do you want to make money?
If you want to write a book, doing so is not difficult. My advice here would be to write something, then find a local writers group in your area. If you happen to live in southern California I can point you to several groups with multiple, published authors who get together every week to be sociable with aspiring authors and help them with their material. Help of that sort is
abundantly available. But to get it you need something to show them. Doesn't have to be much. Spend a couple days and write a chapter.
But, if your expectations are to write a book, have someone else edit it for you, have someone else pay to have it printed, have someone else market and distribute it, then split the money with them....that pretty much doesn't happen unless you're already famous. Also, to even have a work of fiction considered, it's generally expected that it to be complete, finished, polished and done. "Drafts" are for writers groups. Not publishing companies. And even once you've done that, standard practice is to send out a proposal that is basically a sales pitch and a request for them to read your manuscript, which you'll send to them if they want to see it.
Books are available describing the process. Unsolicited manuscripts will generally not be read, but the rules vary depending on what you're writing and who you're sending it to. Writing fiction vs nonfiction, books vs magazines vs television or movie scripts...it doesn't all work the same.
If your goal is not specifically to write a book, but rather to simply to have your work published and be able to call yourself a professional writer, then be aware that is it
vastly easier to have your work printed in a magazine than in book form. And in either case, being able to point to previous successful publications of your work will make it easier to convince others to publish more of your work later.
Magazines are generally happy to review pitches. By all means send out some letters explaining what you intend to do and asking if they'd interested. It's entirely reasonable that you might get some positive responses. For many periodicals, this is standard practice. For example, here are
writer's and proposal submission guidelines for National Geographic Travel.
Here's a list, and here's
anbother list of various travel-related magazines. Go through those, read through their various submission policies and send them prepublication inquiries. It's entirely likely that you might get a few responses back saying
"why, yes, we'd be willing to consider your article for publication once it has been written. Here are our requirements. Contact us again when you're finished." This helps you in several ways. It allows you to avoid wasting a lot of time by, for example...taking your six month trip to Africa, then spending 2 months writing about it only to discover that the magazines that might otherwise have been interested are only willing to consider submissions that are accompanied with pictures with higher digital resolution than the pictures you took. Oops. Or that they would be absolutely interested in publishing an article about a visit to city X that you were considering visiting, but you went to neighboring city Y instead that doesn't interest them. Again, oops. In neither case are they going to promise in advance to print anything to write, but the simple contact in advance can easily help your chances, and if several months later you contact them back with an article and they think,
"oh, hey...I remember this guy. He was going to write about X." that recognition makes them all the more likely to select your piece than if they receive an unsolicited submission from a completely unknown writer.
writing it and publishing it myself as an ebook does sound more attractive.
I recommend you read
this thread. It might anticipate some of your questions, and discusses some issues with the industry that you might benefit from being aware of.