I was idly browsing the David & Charles April 1910 Bradshaw timetable, and noticed that 1 train "terminated", and 11 trains "originated", at Salford (what is now Salford Central) serving the Clifton Junction, Bury, Accrington, Colne line; this behaviour not apparent on other lines through Salford.
This route up to Accrington via Bury to Colne has an interesting history.
Firstly, you may say I can understand Bury to Salford / Manchester, but why Bury to Accrington? The answer lies in the cotton trade and the cotton mills of East Lancashire.
Manchester had the Cotton Exchange, buyers and sellers would gather every Tuesday and Thursday both to buy raw cotton and to sell reems of woven cloth. This buying and selling was done either by the mill owners, someone representing the mill or an agent. To give you an idea of the scale of things, thousands of people would attend the Exchange on those two days. Even small towns had lots of cotton mills, Padiham & Great Harwood (by 1910) had 44 mills in total.
With the line from Bury linking up with the East Lancs line at Accrington, you could comfortably catch a train from say Colne in the morning, conduct your business and be home by early evening.
As far as I know, Salford was only ever a through station.
Many of these train services from Colne did actually terminate at Salford. Back in 1910 it would have been very easy to catch a tram or even a horse drawn cab from Salford station to where you wanted to go.
Where did the ECS trains go? Red Bank? Newton Heath?
I've read a few times the mention of Red Bank, but not Newton Heath.
Can't speak for the Manchester side of things, but Accrington and Colne did have large carriage sheds. Colne especially was know for storing large numbers of empty coaching stock.
Before the days when the service was cut back from Colne to Accrington, up to around the 1920's trains running from Salford / Manchester had slip coaches. If the train was running to Colne but you wanted to get off at Accrington you had to make sure you were in the last two carriages. Coming down the Baxenden bank as the train approached Accrington the guard at the front of those two rear coaches would disconnect from the rest of the train. Then using a manual brake would (hopefully) bring the two coaches to a stand at the station, whilst the rest of the train continued without stopping.
The 1885 WTT show several express goods trains running from Colne on a daily basis. These trains ran in the early hours of the morning carrying all sorts of things including cattle and butter to Salford.
I can't answer the specific questions, but I hope this gives you some sort of picture of what was going on and why.