1: oil leakage so earlier is very bad thing.luckily it got fixed...\
2: if all is sorted out then dont worry ..just enjoy it .. its normal to bee pinched by such things when u pay exhorbitant price and get a boolsheet item..
3: lok at your bikes papers all numbers on it should match hose on bike else ask them to rectify it ..
4: if its in warranty its time to puush a bit its lmits .. i like to test new things as advised for some time when i get sufficient heart on it .. i start pushing it to limits to see if its all ok .. if its ok it will work flawlssly .. its a little bit test that i always do .. so u should use it as advisd for some trime then start pushing it to limits..
4: crankcase is the case which holds the entire gear and other mechanisms .. its just a case .. it it was leaked/broken then obviously chnging it with ok part is natural choice.. if u mean crankshaft (phalla) .. same goes here .. clarify what u mnean by crank
all in all if its in ok condition now .. dont worry .. just carry the above test if u like it ..