Wye Combo / Wye Questions

vertical to horizontal, wye

In an earlier thread this was posted - is this acceptable to attach the outlet end to a horizontal run?

Can a cleanout go on the back end of this fitting?

Can a wye be laid on its side similar to a sanitary tee in a horizontal run similar to this so the end of the combo can be hooked into it?
Old Temp Fix I have to replace about 6' of an old horizontal run that drops into a vertical run. All fixtures are on the floor above the horizontal run, and all the old sanitary tees are on their sides for the other fixtures going in (shower, sink, toilet).

Ideally the plan is remove the entire horizontal run back to the stack if I can. You can see on the right of the picture I linked in that the stub on that sanitary tee is starting to rust bad. I have access to the stack in the attic so I'll be installing a riser clamp up there and in the wall in the room above it as well (so much for my bathroom remodel from a couple of years ago).

whenever two horizontal lines tie together a wye or combo must be used. a santee on it's side is not allowed. Also, a santee can only be used in the vertical position. the combo is the prefered fitting when going from vertical to horizontal and yes, a clean-out can be used on the back.

Thanks for the information Brent - I think I'll go w/the wye as it will give me a more direct line from the toilet.

In that old run there I have a 4" x 4" x 2" SanTee for a sink drain - I'm guessing that should become a wye or combo as well when I replace it.