@1. si, yes, But there is a direct treni di notte Roma-Monaco! Nightjet.

But you could start early in the day, go to f.e. Bologna  and board nighttrain there-travelday counts till arrival next morning.

@2.not in 1 travelday, as any treni you take after 0.00 counts as new day. You have to still use 2 traveldays, but SPLIT this trip: at f.e. Brennero or Tarvisio=1st stop in IT and let day 2 start from there-then you. Perhaps it may be better to simply pay for the last tratte on TrenItalia if this is just short. OR if you can get a cheap advance prezzi and use only 1 travelday to reach Vienna that day and is also valid in the NightJet from there till you get off.

Thank you for your answers. 
Unfortunately I was unable to to find a direct train to Monaco (in Germany of course ) all combinations took me to change train or in Bologna or Padova or Bolzano, could you suggest me how to have this results?

@1 my idea is to travel in the afternoon from Rome to Padova in the afternoon and then take a direct direct night train  to Monaco ( and same from Wien to come back home)

@2 I suspected, maybe I can find some offer if I book in advance

The home country rule is simple - on any 2 of your travel days you can use unlimited trains in your own country in exactly the same way as in all other countries.

So, as you have guessed, the rule to work within is the Travel day rule.

You can use your pass on any participating trains that has a scheduled departure time between 0000 and 2359 CET, even if the journey ends after midnight. Once you leave a train after midnight you require another travel day if you move to a connection. 

So since you are changing to a train scheduled to leave on is before 0000 the next day you do not need to use both home country days.

Obviously if you were to need a later ongoing connection outside your HC that would use one of your remaining travel days.

What is your travel date?

Checked on nightjet website, no availability in my dates (July) so I have to find another solution

Because of engineering works, between 11 June and 10 September, the Nightjet Rome - Munich runs from/to Ancona (via Pesaro, Cattolica-SG Gabicce, Riccione, Rimini and Bologna). If you're coming from Rome and you want to use a night train in that period, you'll need to use another train to reach a night train to Munich. However, Trenitalia is traditionally late publishing their timetables and the July timetable is still not available. I'm afraid it will still take a few months before they publish the summer timetable.

Thank you for the response, oh so that’s why I have no availability 

btw so if I found a night train Wien - Italy (ex. 22.00 - 6.00 am)  then for travel to my final destination I’d have to use another trip day, is it correct?

is there a link to view the entire train map and so try to find the best solution ? because all the planners show not all solutions I think

If you change trains on the arrival day of the night train, then you use a new travel day. You can only travel on a maximum of two travel days in your country of residence. 

You have to be careful when travelling by night train back to your country of residence if you want to change trains to get to your final destination.  Unless you have both your outbound and inbound travel day left, you must use a night train that crosses the border to Italy after midnight. You must then manually enter the night train journey split into two parts. One part from the departure station of the night train to a station outside of your country of residence that the train passes after midnight. Then a second part from that station to the arrival station of the night train. In this way you get the inbound travel day on the correct date and you can continue to travel in your country of residence.