You will only grease them once. They don't move that much. I have driven for at least 4 summers and never an issue. It won't hurt to grease every spring...then it's ready for driving season.
A set of lower rear arms off a 4th gen F body can replace the stock ones. Those are the ones I boxed for my car and they've got the exact same holes for the sway bar ect.
You can modify your stocker by drilling a small hole in the middle and screwing in a zerk fitting. I've always done that if one didn't come installed, works perfect