Hi John,
Sorry, can be a bit slack with responses some times.
It's busy as always and sometimes emails get delayed.
A quick phone call is always the best way to get a response or answers.
Regarding your questions:
No current dip attachment for this rack.
Tail gate delivery is basically using a pallet jack from truck and lowering it down to ground, and moving it as far as possible to where you want it, provided the ground is flat, truck needs access though.
No further unloading is carried out by the driver.
The bumpers, if you get them included in a package are a basic budget bumper plate.
No problems with them so far and don't expect any, especially if mostly for home use/non commercial.
Give us a call if you need to know more.
Thanks