1) good plan, suggest can visit Sienna also (near Florence), if have enought time, can go to Parlemo (capital of Sicily island)

2) can buy over there. Train ticket in Italy is quite cheap compared to other european countries.

3) Roma is better than Milan..... Pls take great caution when in Milan (actually everywhere in Italy)

4) dun know what is 'little lamb'...

5) Pisa is very very near to Florence, even half day can return. Can consider spend another half day in Sienna.