When is the estimated time of the Bitcoin Gold fork?
October 25 according to their website
http://btcgpu.org/And will electrum support the split like they supported bitcoin cash?
Electrum is an open source project and anyone is welcome to fork it and use it for their altcoin. surely someone will do that if there is enough demand and people were willing to run an Electrum server.
the Electrum developer will not support altcoins in the main Electrum repository as he has never done it so far.
so far your only option is to download the main wallet (bitcoin gold core) which is like bitcoin core a full node. with all the options of latest version.
Also is the fork only applicable to bitcoin or also bitcoin cash? Ie if you have 1 btc you will get 1 bitcoin gold, but if you hold 1 bitcoin cash do you also get 1 bitcoin gold or are they now seoerate chains?
as @Denker said above, it is only bitcoin. the airdrops are always with bitcoin