I’m not sure I would bet on the web itself still existing in 100 years. That being said, I think the biggest risk here is your hosting company going out of business, or changing their products such that they won’t host your site anymore.
If you’re OK with your website having a big ugly URL (which might not be a problem if you use a QR code to point to it anyway) then hosting a static website on AWS S3 might be your best bet. There’s so much money flowing into AWS right now, I imagine there will be enough interest to keep it going for several decades to come.
EDITED TO ADD As far as i know you can prepay your AWS bills, so you could prepay a massive amount and hope it outruns future price inflation
It seems the OSM ecosystem already has everything you need. Mapillary, OpenStreetCam or StreetComplete can be used to take geolocated photos that are then used to draw a map. The HOT (Humanitarian OpenStreetMap Team) has organised crowdsourced mapping efforts in Africa for many years now, and has developed open-source software to support those.
I heartily recommend FastMail. I've been using them for a couple years now for all my mail, and they've been great.
They have so many features it's almost comical (it's all in the small details, e.g., you can download your list of last login times as a CSV file; they can SMS you a one-time password if you're in an Internet cafe; etc.).
Once I had a problem with incoming mail from a certain domain not reaching my inbox, and they were extremely helpful. it felt like the guy had nothing else to do but help me. (Oh, and it turned out the problem was on another network, not their end).
In two years I've never experienced any outage.
Really, overall an awesome service (they're not paying me to write this, promise!)
I believe you're thinking of the Voskhod 2 mission. They landed in deep snow in the Urals and had to camp the night out in their spacecraft until the rescue party could reach them the next day.
Alexei Leonov's 1st-person account can be read here: http://tinyurl.com/voskhod2 (taken from the book "Two Sides of the Moon", co-authored with Apollo 15's Dave Scott)
I'd tend to agree with my above sibling that bringing guns in a spaceship sounds like the opposite of safe, but according to Leonov they had a pistol, and "plenty of ammunition".
Edit: others are pointing out that it’s only free for domains with fewer than 10 pwned addresses. I have 8.