‘Contributions’ is correct in this context and, as a term, it is widely used to indicate money (or, more generally, asset) donated to foundations.
Most types of foundations have a minimum 5% annual spending requirement.
5%, that is, of the 12-month average of their asset values in that year.
If the foundation receives a £12m contribution in, say, October, their average asset for that year will go up by £1m (12/12) but they still have to spend of 5% of it. This implies that the return requirement is still 5% of the - now bigger - asset base i.e. as a % of the average asset the return requirement remains the same.
As to the liquidity requirement, from the CFAI book we know that “liquidity requirements are anticipated or unanticipated needs for cash in excess of contributions made to the foundation.”
If a foundation anticipates needing to make a £12m grant in December this would result in a £12m liquidity requirement.
However, if the Foundation receives a cash contribution of £12m in October this contribution reduces the liquidity requirement down to zero (i.e. the foundation has received the money and do not require to create liquidity any longer).
Good luck, Carlo