New Upstairs tub installation

Hi,

I have some questions and would appreciate some help before I embark on a new project.

I have an upstairs bedroom and plan on inproving my en-suite bathroom by adding a tub and expanding the layout.

Questions
1. I plan on teeing into the existing shower hot and cold feed lines and run these to the tub faucet. Is this OK? The drywall is all off and the water lines are accessible.
2. I plan on taking the bath drain and teeing it into the shower drain making sure it slopes 1/4 of an inch per foot. Is this OK and if so do I need a special tee? The shower drain has a 90 degree swept fitting. There is a vent for the shower. Do I need to tee into this also?
3. The floor is particle board so I would like to replace with 3/4 ply to give better support. The bath would be against an outside wall so I don't think the joists need re enforcement?

Apologies for my naivety and thanks in advance!

Thanks Sanjeev for your comments.

Do I need to also provide a bath drain vent as the shower drain that I am splicing into with a swept y fitting has it's own vent?

Thanks

Each fixture needs its own vent. The vents can be combined once it gets run high enough (typically 42" above the floor).

If you re-read answer #2, I stated where and where not to splice into your existing drain line, and that you would need to vent this new tub drain line separately (you can join it with the existing shower vent line inside the wall or in the ceiling).

You have to be really careful how you do this so you don't compromise the venting of the existing shower trap!

Yes,

Your correct. I didn't look at your answer in enough detail. Thank you all.

vent

HOW you do the installation will determine whether the existing shower vent can also be used for the tub or not. Making that decision is why plumbers go to school.