Adding Washer Drain to Existing Stack

[DigitalJim]

As part of my basement laundry room remodel, I want to add a 2” drain line to support a washer standpipe. The washer currently dumps into a laundry tub which drains into a 1½” cast iron tee at the base of the stack, partially buried in the floor. On top of the tee is a cast iron wye to support a cleanout, followed by a PVC fitting and reducer (see picture). The cast iron is all 4” and the PVC is 3”.

My plan is to remove the cast iron wye and transition to a PVC tee using a Fernco fitting into the hub of the cast iron tee that sits at the floor. The new PVC tee will allow connection of the 2” washer drain. I would then locate a new PVC wye and cleanout above the tee. Above the wye I would transition back to the existing 3" PVC stack with a Fernco connector.

I have the following questions about this approach:

1) Is it OK to use a tee to connect the 2” horizontal washer drain to the stack, or must I use a wye fitting? The tee would give me additional clearance to work the drain lines due to its lower profile.
2) Is it OK to locate the cleanout where I suggested? All of my existing stack cleanouts are located right at the floor, but I thought I read that they shoud go above the flood plane of the highest fixture (presumably the the washer stack)?
3) Any problems using a Fernco fitting to connect the PVC to the existing cast iron hub?

Thanks!