Your questions 1-3: these 3 trips do not hang together, you say "two different routes". What exactly is your planned route, and in what order?
The shortest route for Colmar to Turin is Colmar -> Basel -> Milan -> Turin, but a website will give you the quickest route. Look it up on http://www.bahn.de/ This is the best website for train routes and times for international trips.
For actual prices, and for some local companies not shown on http://www.bahn.de/ use the national rail website(s) of the relevant country.
There are lots of different abbreviations for train types, and each train company has their own names for them.
- TER = Train express régional. This is a brand name used by SNCF (= Société nationale des chemins de fer = French National Railways) for a train which is not a TGV (High Speed Train) and is not to or from Paris. It could be a local stopping train, or it could be a 200 Km/h express.
- EC Euro City = an International IC.
- FR = Frecciarossa and Frecciargento high-speed trains operated by Trenitalia (= Italian Railways).
- ICE = Inter City Express This is the brand name used by DB (= Deutsche Bahn = German Railways) for their High Speed trains, travelling at up to 320 Km/h. Equivalent to the French TGV and other names in other countries.
- IC = Intercity. A brand name used in many countries for fast trains only stopping in big cities. 'Fast' can mean 200 Km/h, but not as fast as High Speed trains which run on specially built tracks at up to 320 Km/h.
The railway company websites usually give an explanation of all these terms.
"Is going through Switerland by train more difficult than thru France?" not particularly. If you go to http://www.bahn.de/ or any other railway company website, and put in your 'from' and 'to' stations, it will find the quickest route.
