Opamp input bias current

[Kimly]

Do bias current of opamp flow into inverting & non-inverting terminal? how to determine in which direction current will flow.

[Jerry]

I'm not quite sure why you would want to be calculating the input current at the inverting and non-inverting inputs.  Remember that an ideal op amp has infinite input resistance which would mean the ideal input current would be zero.  Take a look at the op amp circuit below.  It has ground on the non-inverting input.  What's the voltage on the inverting input?  That would be zero.  It would be a virtual ground.  So thinking of it as ground on both the inputs, you would not have any input current.  Of course we know that is the ideal situation and that in reality there is some tiny amount of current, but it is insignificant.