Olee Sleep 4 Inch Tri Folding Memory Foam Topper Blue, Full

Does it bottom out on hard floor?

Is that mattress Gueen size ?

Is this the size of a crib sheet? or regular twin sheets? i've never heard or seen tri folding sheets? where can i find sheets for this specific item?

What's the difference between the blue &a the grey? the price goes up really high for the grey one. but doesn't seem to change anything else?