Track - Sleepers and Chairs and other stuff

I'm nearing the point of placing an order for track components so need to put some thoughts down to the type of sleepers and chairs that I'm going to use.

Sleeper type, plastic or wood?
Wooden sleepers would be my preference as I feel they will give a more natural feel to the track work. On the other hand as I have not built any track for some considerable time A plastic kit might be a good starting point (no pun intended). At this moment, in drawing the track plan, there would not seem to be many points at Grogley that suit an of the standard "out of the box" kits. The main junction will have to be bespoke.

This has started me thinking that I may build a little 6 x 1 ft test layout using a couple of kits and then building a couple of bespoke points using wooden sleepers. This would give me a chance to iron out any problems before embarking on the main project.

Sleepers size and length?
My understanding on the sleeper wide is 10" for plain track, 12" for turnouts. But were 12" sleepers used on joints on plain track? Regarding length, as the track had been relayed at least twice before the 1960's the sleepers should be 8'6" long.

Chairs, Standard 3 bolt or LSWR?
From photos it looks like Wadebridge had the standard 3 colt chair in 1959, though the Wenford Bridge branch still had the LSWR chairs in 1962. As yet I have not been able to confirm Grogley after 1933 when it still had LSWR Chairs, but it looks like Boscarne had the standard chair in 1962. So I've settled on the standard 3 bolt "S1" Chairs for the main running lines though the junction. (That is 1 bolt on the outside and 2 bolts inside).

A cat among the pigeons
With all the above said I have I've seen a colour slide that looks like Dunmere junction may have had concrete sleepers in June 1960. I am also certain I have a B/W photo somewhere of the junction outside Wadebridge circa 1960 that seemed to showed concrete sleepers on the Bodmin section. Makes me think:
Q1) I could justify laying the plain track leaving the junction towards Bodmin with concrete sleepers?
A1) I think the answer to the above question is yes but no. After reading Colin Craig's article, mentioned below, I feel that with no detailed information as to the exact type of concrete sleeper and rail used on the branch I cannot justify any on the model.
Q2) So when did BR introduce concrete sleepers and on what lines first?
Q3) Were concrete sleepers laid on branch lines first as tests before being used on mainlines?
Q4) When did flat bottom rail start to be used....was this at the start of the introduction of concrete sleepers?
All of the answers to the last three questions above can be found in an excellent article by Colin Craig from the MMRS at http://www.mmrs.org.uk/technical/track.html