Yes, however is one word.
no
I've used my computer ever since I bought it.
Ever since the first time it was said.
Whoever is one word and is pronounced like "hoo ever."
There are many examples for the word "ever" in a sentence, one of them being, How will we ever learn to play the guitar?
whenever is one word.
"Where ever" should be spelled as one word. "Wherever you are" and "wherever I am" are correct.
It is one word, the compound word "bathroom." This American euphemism for a 'lavatory' has been confusing British travelers ever since it's 1780 adoption into the lexicon. See the related link listed below for more information:
There are 2 in ever ... eh-ver
one
Yes, since 1943.