Hey,
first, note that running on the latest version of openrouteservice will speed up builds by quite a bit. Make sure to update or pull the latest docker image 
Second, if you’re running the whole of europe with all 9 profiles, then this will take more than 20 GB of RAM (we recommend twice the amount of RAM as the file size) and probably a build time of around two days, maybe more.
Build time for the openpoiservice is quite a bit longer, so this is to be expected.
We run the openpoiservice build on a by-country basis, running it for the whole of Europe could easily take a week…
The main question here is whether you actually need all profiles, and whether you can sacrifice request speed for build speed - if you can, then turning off some preparations might speed up the build significantly.
Yes, if you want to restart the server you have to rerun the containers.
The ors data is stored in a custom format in the graphs-folders.
Make sure that they are persisted to disk via docker volumes as is done in the docker-compose.yml-file.
If this happens, reloading shouldn’t take more than a few minutes.
For the openpoiservice, everything is stored in the postgres database so persisting that in any way should work.
Best regards