photo and auto in same box

I don't think it's critical. Autoflowering strains might slow down weight gain a bit.

Not much at all If provided the correct DLI

you will lose a good 30% of yield and you buds will be more airy.

thank you, thought it made a huge difference, for example 2x or more

I believe none except the minor yield. I hope I have been helpful

You yield will suffer with the autos, that’s about it. Less sunlight = less growth for your autos generating less final product from them. On the other hand, your photoperiod plants need the 12/12 to flower, so unless you have a second grow space the autos will have to take the loss, the plants will stay healthy, they just wont produce as much.