A toilet floor drain pipe is to be used with 2" pvc pipe,can it be posible?

I believe you will find the minimum size is 3", 4 would be better.

Not sure I 100% understand your question... but...

Yes, you can have 2" floor drain. Make sure you install trap as well

Yes, you can connect floor drain pipe to an existing toilet drain - but I highly suggest you vent and prime this floor drain

No, you cannot use 2" drain for toilet

Hope that covers it all

Milo

Maybe I missed this but the 2" is a drain, not the toilet drain. Maybe you can better describe what you have and want.