Basement plumbing question

[marek]

I am adding a washroom in the basement and have a question about the standpipe for the washer and the drain for the toilet.

1. My toilet placement will be 9' from the stack and almost directly in line with a shower drain (See diagram #1) . How do I run the two to the stack (looking for a diagram)?

2. I plan on adding a nice laundry center setup in the wall and have a diagram of a proposed layout (Diagram #2 and #3). Would this layout be correct (There is obviously a p-trap on both the sink and the standpipe)?
I realize that a 2" pipe calls for a 1.5" vent but I have an older house that has a 1.25" vent. I would have to rip out existing walls and an existing upstairs shower to replace it with 1.5", as there is no access (side split house), and yes I checked the attic.
Can I still use the 1.25" vent with the 2" pipe? I had the same model washer/dryer in my condo and it drained into a 1.5" standpipe without issues (instructions call for 2" though)

Any help would be appreciated.

[cacher_chick]

You bathroom and your laundry traps will all require venting beyond that of a 1-1/4" vent.

I'm not sure what you are referring to by "the stack". The new bathroom drain connection will need to be made to the horizontal building drain under the floor, so where the existing stack is located is irrelevant.

The water closet can be wet vented by the lavatory's vent. The shower will need a vertical vent take-off upstream of the connection to the main line.