Those are all really good questions that most writers on Medium have to think about!
I don’t think there’s is a right amount per se. If you want to get more traffic I do think that it’s necessary to write almost daily, because you’re more likely to get discovered. That being said, being discovered is not that rewarding. I get 10,000 views a week and do not receive any monetary value from it because “feedback” is what gets you the $$$. So, depends on what you want.
Recipes can do really well! It’s all about finding your niche topic. That is how you get fans that stick around because they know they’ll get consistent themes from you. I am still learning how to do this well.
Facebook & Twitter is how I share my articles. You can get into newsletters especially if you’re doing recipes. That would be a very good idea.
Hope that helps for now. Let me know if there’s anything else!