I'm putting a second full bath in our (soon to be) finished basement. I've got a 6' ceiling, so I'm cracking the floor and putting the pipes in cement.

My problems or concerns revolve around venting.

I'm going to tie in about 8' from where the stack goes into the floor from upstairs, and then runs across the house to go out. I am able to tie into this about 8 feet from the pipe vertical.

It's a 4"+ (black iron-galvanized?) pipe, so if I use a 4" toilet I make the critical distance, but the vent is upstream. The sink and shower are worse. I've got to run several feet to even get to the main pipe.

What are my venting options?

After the critical distance, can I run vent pipes up the walls of the new bathroom at a 45 degree angle to line them up for going up another floor? Can my critical distance or horizontal pipe be anywhere along the path? (specifically there, I'm thinking can I run a 45 up the wall, and then horizontal to the stand pipe so it's overhead in the joist over a hallway)?

Am I allowed to tie a vent pipe in below drain connections from higher floors? I'm thinking that I would need to run a 45 to meet the horizontal distance, and then tie into the stack. Can I do that, or do I need to make those connections in the attic if I want only one roof hole?

I realize it's a lot of questions, but I'm trying to find out what all of my options are here.

Thanks in advance.