Meanings and origins - seer???

can anyone give me the meanig and orgin of the following prases, "bank teller" "sleep like a top" and"greenhorn"

A bank teller is a person who works behind the counter in a bank, serving customers. An old meaning of "tell" was "count," and tellers count money.
To sleep like a top is to sleep very deeply and soundly. I don't know why that's called sleeping like a top. Possibly the reason is that when a spinning top (the child's toy) stops spinning, it comes to a complete stop and lies utterly still.
A greenhorn is a recent immigrant who hasn't yet learned the ways of his or her new country, or, more generally, anyone who is inexperienced, immature, or gullible. The word originally referred to young animals with immature horns, like deer and elk.

Also, the use of green to denote immaturity comes from the woods. Green timber being that which isn't yet seasoned. Hence the rhyme relating to ash, which burns especially well:

Seer or green,
fit for a queen

(seer = seasoned)

or alternatively:

wet or dry,
fit for a queen to warm her slippers by.

I thought that seer (or as I know it, sere) meant dry or desiccated - with added connotations of decayed. There's a quotation from Macbeth that supports this, if the word is the same one:-

"I have lived long enough: my way of life
Is fall'n into the sere, the yellow leaf,
And that which should accompany old age,
As honour, love, obedience, troops of friends,
I must not look to have.'