Legion launch questions

[Dainichi]

Hi, im new to WoW Freakz and im wondering about the supposed "Character transfer" thats gonna be available sometime after launch of Legion, I have a question regarding it.

If I make a character at launch and test out the server, Will I still be Eligible to transfer a character from another server?

and another question about acquiring Challenge mode Sets from MoP or Challenge mode Weapons from WoD

Are they obtainable for free in Legion, or do we have to Buy them with Points from the shop?

and lastly about the Client and Files

After launch do we need to Download a fresh launcher or we can still use the one for PTR?

-Thanks to whoever can answer these <3