No.
They will fit if you will have to tuck the extra length in at the bottom.
A regular twin bed is only 74 inches long. An XL twin is 80 inches long. So the answer is NO.
No, they will be too short. A Cal King sheet would fit on both twin beds, if they are pushed together.
When I was a child in the 60s and early 70s, before fitted sheets existed, we used sheets that were 72 x 108 on the mattresses of our twin beds. We used them as the bottom sheets, not the top sheets. We put them on using "hospital corners." On change-the-sheets day, I remember looking through the cupboard of sheets at the tags on the sheets looking for "72 x 108." 72 x 108 provides about 10 inches to tuck under each side of a twin mattress.
A couple can't fit in a twin size bed. Only one person can.
No
No. Two twin size mattress will fit a king size bed frame.
A twin bed is smaller and made to fit one person. A full bed is made to fit two people, and it's bigger.
yes they will fit in witdth, but not in length
Yes
No. Two twin size mattress will fit a king size bed frame.