Customers have a reasonable basis to ask for borrow pricing daily because rates and availability change frequently, and the cost of the short is one of the factors influencing the decision whether to trade it or not.

A locate request is basically "hey do you have shares to lend out, or can you find some?"

It makes total sense that FTD would affect shorted stocks, because it generally arises from a short sale and the heavily shorted names are the ones where borrow is tight.