Q1: Yes, provided they give you your contractual notice period between advising you of the new policy and actually wanting to use it.
Q2: Impossible to answer because it is up to the company to determine this and let you know. Many companies operate a 'day for a day' on holiday (i.e. 5 days notice for wanting a week's holiday) but yours is obviously fairly fussy about wanting to know well in advance. It would seem probable that they would want to apply the same 'rules' to lieu days as to holiday.