ManfrottoMH496 BHUS Center Ball Head, Black, MH496 BHUS

Q: Does this mount on slik pro dx700 tripod?

If the SLIK has a standard 1/4 or 3/8" screwhead, then yes.

Q: Arca swiss adapter ball head 496 how do you connect l bracket need arcaswiss with this ball head 496 ? is there adapter and which exactly ?

Manfrotto makes an Acra Swiss plate that can be used without an adaptor. There are many other companies that do the same. Search Amazon for "arca swiss plate for manfrotto.

Q: What is the function of the smaller knob, located lower/ the opposite side of the larger knob that tightens/loosens the head?

That is a friction knob, the purpose of which is to enable movement of your camera but upon release, it stays put. It's a function that's best suited for when you may need to reframe things quickly, yet still need the stability of a tripod.