1- minun pientä kissani on kaunis : my little cat is beautiful !!!!!!!!!!!!!!!!
nearly, minun pieni kissani on kaunis!
was that right ???
2- minun taloni on iso : my house is big !
yesss
3- minun toverini on upea : my friend is great
yes, but i'd prefer 'kaverini'.. toveri is such an old word..
so .. are these right ?
nearly 
"my little cat" is just simply "minun pieni kissani" paritive is used much only with verbs.