This should be Hungary's flag. It was used by the Habsburgs, and since there'll probably be a Habsburg on the throne (maybe II. Ferenc Ferdinand?
), that'd be the flag they'd use. For Serbia, I pasted together
a flag in five minutes out of the Serbian civil flag (the Serbian tricolour has existed since 1835) and the royal coat of arms. Croatia can be
this; it was used by the Habsburgs, but I think it fits a republic just as well. Slovenia and Slovakia I don't know about.
As for the peace treaty, I think:
- Abandonment of Peruvian claims on Arica and Tacna (both of which were Chilean at the time).
- Favourable border settlements for Ecuador against Peru and for Paraguay (they were in the Free Americas, right?) against Bolivia.
- Restrictions on the Peruvian and Bolivian militaries.
- Free elections to be held in both countries.
- Limited war reparations for Peru and Bolivia.