Mattress sizes are notoriously confusing, but in general, a "double" is significantly wider (as in, over a foot wider) than a twin and will not fit on a twin frame.
That's the standard double bed width in the UK. Anything bigger has a fancy name and you would do well to measure the dimensions.
It really depends on the mattress and the sheets, but my guess would be no.
A twin mattress is 75 inches long and 38 inches wide. This is smaller than a double bed, and is considered a bed for a child. Two adults would not fit on a twin size bed.
Try it and get back to me by asking another question or googling it
Yes. We just did this three weeks ago in our 2002 Olds Silhouette. On an angle, box spring first, then mattress on top of that. Tight but no problem.
If your rear seats can be removed or fold flush with the floor: absolutely. I load them daily.
No, it wouldn't fit
they are microscopic. they fit through microscopic holes in the mattress.
Most likely what would fit in a mini camera would be either a Micro SD which are the smallest or Mini SD depending on the size of the SD Slot. and how much storage you want depends on the brand
no
If the bed has a metal frame, it may be adjustable. Check to see if the bottom and top rails are in two parts with removable bolts holding them together. You need to be able to make it 6 inches wider. If it's a wooden bed with a headboard and footboard, you won't be able to make it any wider. The queen mattress would stick out on either side so you won't be able to use the extra width of your mattress. (Also, it wouldn't look very good.) On a platform bed, you may be able to fit a queen mattress if the platform is more than six inches wider than the double mattress. The queen mattress will just cover more of the platform. The only way to be sure is to measure the mattress and your bed.