What Am I Riddles

Question: My name can have any letter of the alphabet, but I always have 2 X's.

What am I?

Question: Take my first and make it my last, now I happened in the past.

What am I?

Question: Some use me, while others do not.
Some remember, while others have forgot.
For profit and gain I'm used expertly, I can't be picked off the ground or tossed in the sea.
Only gained through patience and time, can you unravel my rhyme?

Question: I have eight to spare and am covered with hair.

What am I?

Question: I brighten your day but live in the shade.

What am I?