2. Possibly, try to get a domain of your own, and preferably a `.com`. Point that to whichever server you use (if they don't allow you to point, that is a net negative). Keep pointing to the services that you keep moving as they keep dying. One day, you might just end up writing in plain HTML and (s)FTP into a folder.
3. If you are going to use images/audio/video quite a tad more than usual -- start using a CDN (pretty cheap and some are free these days). If those are hosted on https://cdn.mydomain.com, you can move your content wherever you want and those images, audio, video just works. I was able to change WordPress hosting providers in minutes because I don't have to move the static assets.
edit: added the 3rd point.