It comes with 3 matching screws.
Product details says, "Includes 1 open-lip and 1 closed-lip socket".
yes screws are included. Three vice the one original.
I'm not sure what the weight specs are But a lot Would have to do with The selection And type of Pole You use, And the mounting surface IE Are you mounting Your brackets to sheet rock, wall studs or what I do is mount a 1X.3 Across several Wall studs And place My bracket On the 1X3 This helps Secure And strengthen Your brackets
First you install the pole into the closed end piece then you slide the pole into the open ended piece.
it's about 1/8 - 3/16 inch thick.