I've hiked in a couple of countries in Europe, especially France, for a number of years. Never had a problem. I just ensure I have my back and forth tickets and of course my passport. My travel insurance is paid for by my monthly current account charge, I think a good deal, £10 a month for travel insurance abroad and AA car cover in UK.
I have an Osprey Exos 48. I pack everything inside the rucksack, including poles and when I take it to go in the hold I reverse the hip strap and pull it tight then tighten every other strap.
Being older helps me I think, I am always treated well by all of the nationalities I meet. I make use of buses if I need to, trains as well. Hitchhiking can be a bit hit and miss, not so good if the driver and I cannot communicate.
I only seem to have a problem when I need to cross Paris, I'm not so good at understanding their Metro layout.
So easy to follow a French long distance hiking route, just look for little horizontal red and white paint flashes on rocks, walls, lamposts, trees and so on. If you see a red and white cross along your router, don't go that way. Actual signs are used when two or more footpaths cross over each other, I find it hard to get lost with their system. One small thing, easy to make an error, if after a long days footpath walking, to forget that the traffic is on the other side of the road when you need to cross or walk along tarmac.
I camp and will tend to look for municipal sites first, they tend to be cheap, the more commercial sites designed for static caravan and tents tend to be fairly expensive. Apart from these few items hiking is the same as here.