Alfonso is a great starter name. :)
I've been experimenting with sourdough the past month, too, and have found this experience with Mike Francis (my starter!) to be much better than the last time I tried, with Fidough (RIP). I've been using Emilie Raffa's excellent book Artisan Sourdough Made Simple as a guide, and it truly does live up to the title. I'd also pay twice the amount of the list price to have such clear, easy-to-follow directions -- with pictures that show you exactly what you're doing! -- instead of scrolling through alllllll the ridiculous amounts of info and tips online. I strongly suggest getting this book.
To answer one of your questions, based on my experiences:
You can mix things up with feeding, but using unbleached all-purpose flour is generally recommended. (But once I ran out of flour once and used bread flour, then ran out of bread flour and used whole-wheat, and the starter is still perfectly fine.) Also know that you can turn some of your starter into a different flour-type, say, rye, if you want to try making a sourdough rye. (I'm working my way up to this Danish rye bread, for example.)
I started with a mature starter (given to me by a friend), so I'd defer to Raffa and her FAQ section on how to tell when your newly made starter is ready to be used. Ditto on the increasing/decreasing question.
(Also another thing about her book: She includes a chapter on what to do with the portion of starter that you discard -- I made some stellar yogurt flatbread with some the other night, and have some cracker dough waiting to be baked.)
One more thing that has markedly improved my experience this go-round: I got a digital kitchen scale, for ease of feeding and precision of measuring, and a Dutch oven, for baking the bread in. (Which Raffa also recommends.)
Source : https://live.washingtonpost.com/free-range-1-24-2017.html