Adding a Bathroom to a bungalow attic - Toilet Venting Question

Here is what my stack looks like so far...I did go with the 2" low-heel connection, just to be safe. My major focus is on around this 3" street 90 closet bend.

What you have there in the picture is good.

My old cast iron 4" main stack does not have a clean plug, but I am going to add one in my remodel. Does my new secondary 3" stack going up to the attic also have to include a cleanout plug? Or does the cleanout on main stack serve as the cleanout for that stack as well? Lastly, where do these test tees go? Are they mandatory?

EDIT: I have had (2) plumbers tell me that toilet is actually a cleanout on a vertical run, which makes sense, because if the toilet is removed, I could easily snake this 3" secondary stack. Understanding again, that this may not be the ideal location. However, I am tight for space in the basement and do no want to add another 3" tee or wye in my secondary stack if I do not have to.

where impractical to install a vent the toilet may be used as a clean out.

Wow, big weekend....I tapped in the main stack yesterday. Good news, NO LEAKS! Please take a look at the photo. I am thinking I need to add a test at the end of the 2" run that goes back towards the other side of the basement. At that point, the pipe turns at 90 degrees and goes another 6' between the floor joist before it goes straight up to the bathroom. From the code book I read yesterday, it seems that I need a test tee whenever there is a horizontal change in direction of 45 degrees or more. Can someone confirm that. Also, where the vertical pipe enters the basement for my separate lav/shower 2" drains, are long 90s okay there, or do those also HAVE to be test tees?

EDIT: Sorry Terry, even the largest plumbing supply house did not have the cast iron wye I needed for this project. They guys told me that no plumbers in this area are using cast iron for home replacements anymore, so they do not carry it.