Bovine gelatine is a by-product of cattle slaughter in which connective tissues are made into gelatine, a thickening agent for foods.

if it says halal gelatine then it is, or if it is not from beef it is halal, e.g. beef gelatine (haram) , gelatine (half-half) and last but not least halal beef/non-beef gelatine (halal)

Yes, drumsticks contain gelatine.

I buy Davis Gelatine where there there is written "This Gelatine is purely extracted from Halal slaughtered beef." Therefore, it's HALAL.

No, it doesn't contain milk or gelatine.