I don't have Forsaken Addon on Blizzard.net. Will I get it if I pre-order Shadowkeep on Steam? Or it will be free?
Or I can buy it now on Blizzard.net, complete and all the data will be transferred on 1st October?
It is not (and likely will never be) free, nor is it included in any current Shadowkeep bundles. If you want it, you’ll need to buy it from blizzard now, or wait for the transfer to steam then buy on steam.