As regards the chain maintenance, what do you do now?
Do you monitor the distance or have a set timeframe?
How about pretending you're on tour and using whatever you think you will have with you?
For me it's a rag and a bottle of lube. At home? Not much more.
Videos are good as we can slow them down to our pace. I believe you can save Youtube videos for offline use.
I also make short notes on the things I know will trip me up.
Do you actually practice on your bike while watching/after the video? There's a world of difference between the theory and the practice and "studio conditions" are never quite the same as road conditions.
Finding that tiny piece of wire that punctured this tube and will puncture my new one may not be so easy!
I can't comment on park camping but I can comment on safety. "Over there" is always more dangerous than "here", or at least that's what people tell me. It's not my experience.The fact is, most people are friendly and hospitable. The ones that aren't can be usually picked out if we keep our wits about us.
I always think the most important thing to pack is a smile - it opens so many doors.
Your greatest risk will be vehicles.
I've read of more than a few touring cyclists who complain of having to be friendly to helpful locals at the end of a tough day!

I may have the wrong end of the stick but I found your title to be a tad dramatic in relation to the subject matter. A little anxiety is normal, it's when it gets out of control that it can hamper us.
The best thing I can recommend is to practise. Ride to a friend's house to camp out in his yard. Storm coming in? Out with the tent and see how much fun it is to set up!
Too hot/wet to ride? Replace the front tube with the rear one.
The more we do, the less fear we lug along with us.
I am no mechanic and before heading off into parts unknown I cycled out to a local forest with my "touring" tools and did everything I could think of to the bike. It was slow, cumbersome, not a lot of fun but incredibly rewarding.
If you're not familiar, CrazyGuyOnABike is a treasure trove of cycling journals with a useful search function. Loads of information but more importantly, tonnes of inspiration!
Good luck!