Basically Base Rate is more fluctuate than Base Lending Rate, rather than Bank Negara Fixing the Base Lending Rate, Base Rate is revised every three months depending on the economy at that moment. In short, Base Rate will influence by the economy, when economy is good, Base Rate will be lower and the other side.
from personal experience, if the interest adjusted does not hit amount installment adjustment amount. The bank will not give you the option to reduce your installment?
However, the good news is you will definitely repay your loan sooner than the initial tenure as you are effectively paying "extra" every month towards your loan principle every month.