I have been watching videos, reading the forum and looking at everything I can to help me figure out how to use signals properly. But I am still not able to do what I want and I am seeking some advice please.

So I have trains traveling from Point 1 to Point 3, Point 2 to Point 3, Point 2 to 1 and Point 1 to 2.
All I want to do is make it so that trains that travel from Point 1 to 3 and Point 2 to 3 dont run into each other at the track joint 3.
The problem is that the signals create/join 2 blocks, one before and one after. I want to put a signal between point 1-3 and 2-3 with one at the exit of 3 to create a block just at the junction. The problem with that is that the block at 3 looks forward and goes red if any train is past that block which is not what I want. I want as many trains as they want to go onto the rail at line 3 and just form a line.
Please ask questions because I feel like I have done a really poor job at explaining this.
As a second question, is there a way to ensure a gap between trains on my main line?