Most railway companies in Europe offer facilities for disabled passengers. Standards vary between countries.
No. Most trains in Europe only transport passengers, luggage and often bicycles, but not cars or motorbikes. There are a few trains on selected routes that offer the option to transport cars.
EuroNight is a general term used for national and international night train services operating in Europe. The Berlin Night Express between Berlin (Germany) and Malmö (Sweden) is an example of a EuroNight train.
Most train stations in Europe have a lost luggage department. If you aren't near the location where you lost your property, try to contact the railway company you traveled with.