Did not use the hose clamp method as I was concerned of the plastic/composite material being old and brittle from high coolant temps so it might break again soon.
Interesting tip about expansion tank cap, thank you.
Drained from red plug located in lower radiator corner (passenger side), additional coolant was drained from the system after removing the old hose.
Did not bother the complication of removing the engine block drain plug but is there 1 on passenger's side as well?
It took exactly 2 gal (1 BMW coolant + 1 distilled water) to fill completely.
Initially when starting the engine, the electric cooling fan stayed on and after few minutes turned OFF.