Steam – Company of Heroes and Company of Heroes tales of valor

Will Creating a 2nd steam account work on the same computer / will i be able to play tf2 with the already downloaded version as an f2p on the new account, or will i have to download a 2nd verion of tf2 for the same computer?

The currently downloaded version of TF2 will do. You do not ostensibly need to download a different version for different accounts.

If so, i know my items would not be affected because of the cloud but would this be considered cheating towards VAC

No. Items are bound to accounts. Different accounts have different inventories and trading them between accounts involves being logged in with both Steam accounts at the same time.

would this be considered cheating towards VAC

We can't tell you. Steam probably has ways to know what you're up to, but so far has ostensibly done nothing about it.

how will i tell the difference between that and the Version i payed for years ago?

One has the Proof of Purchase, the other won't.

I think the following is the correct way to currently do what I wanted:

1. Ensure that Steam thinks the game is not installed. Close Steam just to be sure.
2. Copy the game files to SteamApps\common\<game_name>, where <game_name> is to be found out via googling/equivalent. In my specific instance, this was Batman Arkham City GOTY.
3. Launch Steam and install the game. The installation will go through a "Discovering existing files for _" stage.
4. Watch and wait as it downloads only the missing parts.

I still have to download 9.8 GB though (instead of 17) in my specific case.