The London to Brighton route has been in the game from 2012 that is 7 years ago the route will need redevelop the Brighton mainline and Arun valley line and South london metro and the Epsom Downs branch and Leatherhead branch Tattenham corner and Caterham branch lines and from London victoria the route has to been from the modern day and the route needs to be done for at some point this year the trains run on the trains the class 377 class 455 and class 456
Yes, the 456s transferred to South West to bolster their suburban services though with the upcoming replacement of 455/456/458/707s with Aventras, it wouldn't surprise me to see them back on the Southern at some point. Especially as the 313s are now approaching their 45th birthdays.
It's alright, I'm from north of the Thames, worked on the railway and lived in London for 21 years and still the Southern seems like a foreign land to me.