Compare two data tables

First off, I'm thankful I found this forum and thanks in advance for those that are able to help...

Any help would definitely be appreciated.. I've been stuck on this for hours and I'm just not sure which values to use...

I have two different data sheets with data on them...
Column A is the unique ID
Column B is the variable I need to compare


Sheet 1: Data Feed
A B
1 in stock
2 out of stock
3 in stock
4 pre-ordered

Sheet 2: Current Inventory List
A B
1 out of stock
2 out of stock
5 pre-ordered.

Problem 1:
Now from these two sheets, I'm trying to show on Sheet 1: Data Feed, which one of these values are not in my current inventory list.. So I was thinking I could have a Column C: that would note with a boolean value whether or not the row exists in Sheet 2. So in this case row 3 and 4 on Sheet 1 would say (no or some other boolean value) in column C.
I tried this... =LOOKUP(A2,Sheet2!A:A) but it's not pulling up the right values...


Problem 2:
I'm trying to update the stock on Sheet 2, based on Sheet 1. So after comparing the two, on column C for Sheet 2, I can put the new stock value and then just copy it over to column B.

I tried this: =VLOOKUP(A2,Sheet1!A:A,2,FALSE) on column C of sheet 2, but it only brings up #ref and #n/a values...

I guess my question is... what formulas do I use? I have attached the two sheets..

Thanks in advance once again...