New to smashburgers

Several questions.. I’m a blackstone NOOB, so please take it easy and give me as much advice as possible. THANK YOU!!!!

1) My smash burgers always end up cold. How can I avoid serving my guests cold burgers? 2) I can’t figure out how to time up my onions on the grill to finish while my burgers do. How can I time these up with my patties? (And again keep everything from going cold?) 3) Do you use anything along with your buns on the grill, such as butter, mayo, etc? I’ve just been putting them on the grill over where the patties grilled, but it leads to uneven toasting. 4) Any advice for more even heat distribution across the grill? The center is super hot, the edges not so much. 5) My blackstone pools oil in the back left corner. Is there anything I can do to redirect the excess oil into the drip tray?