I’ll try this one for you, Dan; I have most of the morning… First of all, this is only a theoretical exercise, because railroad rules vary, and some of the railroads in the real world would have noting to do with, for example, lunar white lights. Your main lines also have to be signaled beyond this interlocking–in other words, this network of signals will not exist in isolation from the rest of the railroad. There will be distant signals a block away in either direction on the main lines.
First of all, Signal 4 is unnecessary.
Signals 1, 2, 5, and 6 will each have three heads, the top two of which will be capable of displaying red, yellow, and green, and the bottom one red and probably lunar white. Everything would face away from the switches, to “protect” them.
Signal 3 would be a two-headed signal. The top head will always be red, the bottom will be capable of displaying green, yellow, red, or lunar white.
All of these signals would be absolute signals, so no number plates should be in evidence.
Your question 1: Correct, except that 4 won’t exist; 3, 5, and 6 will face RR West.
Your question 2: Both heads of Signal 3 would be red most of the time. When your train is lined up to leave the siding, you could get a green (track clear beyond the signal), yellow (next signal will be red), or lunar (block ahead has train, engine, or broken rail).
Your questions 3 and 4: Signal 1 would govern everything for trains coming from that direction. On Signal 1, a yellow or green on the top head would indicate a routing through to 5; a yellow or green on the middle head would be a lineup to 6 (in both cases, dependent on conditions in the block beyond the next signal down the line), and a lunar on the lower head would indicate a route from 1 to 3, assuming your siding is not protected by the signal system.
Your question 4: For Signals 1, 2, 5, and 6, the middle head will govern the crossovers, telling the train to proceed through the crossover at th