however, since we are pre-investing (expecting an inflow of cash in the near future), where do we get the money now to buy the relevant stock and bond futures?
Additionally, the cost of borrowing is not reflected, at least not explicitly, stated in the examples. Can someone assist on the two fronts?
If you expect the cash in 3 months, then you buy a 3 month futures contract. The contract doesn’t settle (i.e. you don’t pay) for 3 months when you’ve actually received the cash.
The difference between this and purchasing a futures when you already have the cash is the risk free rate (if you had the cash today, you would earn the risk free rate between now and the contract settlement).