Generally painting over prior paint will seal in the VOCs.
I would still suggest you vent the house for a couple weeks prior to painting which means windows open, fans on to circulate a lot of fresh air through the place and remove the VOCs. After about two weeks of this, you will have vented a substantial portion of any VOCs and can paint over and seal in the rest.
Regarding the new floor, it depends on what it is, wood, tile, painted or prefinished composite/engineered system. Without knowing what's installed exactly that is a harder question to answer.
For more information:
Debbie Sek recommends ventilation in her Q&A "Our painter used traditional paints instead of non-VOC. Should we strip the walls and start over?"
Read Steve Rush's Q&A "How do you remove or encapsulate non-green wall and floor finishes?"