Hi Julie,
1- Don’t be peturbed by the near-total absence of obligatory reservations in Germany - it’s a good thing, and a nice throwback to the totally spontaneous Interrail experience of yesteryear! It also makes Germany one of the very best value places to use a pass.
If you don’t buy reservations you do run the risk of not being able to find a seat (or not being able to sit together in a group), but realistically this will be the exception rather than the rule. Maybe make reservations for a couple of long-distance trips at peak commuting hours, but otherwise don’t worry too much about it. Unlike in the UK where I am, in Germany many trains are double-deckers, which helps to accommodate more people.
2- Interrail reservations are always the same flat rate, which is based on the category of train rather than the distance. This makes some countries less economical than others. The absolute worst is Spain, where €4 is charged for almost every regional train, and the traveller almost seems to be monetarily penalised for going off the beaten track.
But Italy is better than that. In normal times, the only trains there that are obligatory-reservation are the high-speed trains (Frecciarossa, Frecciargento and Frecciabianca), which cost €10 each. It’s not good value to pay this for a short trip like Venice to Verona, but it definitely is when travelling further, i.e. to Rome or Naples. Booking any train through the Interrail booking service will incur an extra €2 booking fee per train, but booking in person at an Italian station does not.
Anything else should be free, although because of the pandemic and social-distancing, some regional trains (RV/RE) have been made temporarily reservation-obligatory and are subject to a €3 fee.
Intercity (IC) trains are a special case - these are always obligatory-reservation for ordinary passengers, but Interrail passholders can board them without reservation, though they may have to keep changing seats because those reserved by others will not be indicated! If you want to avoid this, reservations are €3. The nuance of this irregular situation is unlikely to be reflected in the Interrail timetable app, but it does apply nevertheless.
Speaking of the app - if you look to the left of the screen, below the destinations bar and above the train times, you’ll see a tab labelled “Reservation Type”. If you click it and then click “No seat reservations required”, you will be shown only trains which don’t require reservation. There are reservation-free direct regional trains between Venezia Santa Lucia and Verona every hour at --:10 :-)
Thank you so much for your help guys !!
2- Interrail reservations are always the same flat rate, which is based on the category of train rather than the distance.
international TGVs to/from France are an exception because they have variable rates according to the distance (and often quite expensive) and a limited quota for Interrail/Eurail reservations.