Can I recreate a wallet using on my priv/pub keys only? If I lose my wallet (let's say it is hosted with a company that went bust) can I recreate that same wallet with another provider using only the private/public key pair I had with my original wallet?
Yes, you can create a wallet with your key and will have access to the coins at the key's address.
Since a wallet typically contains many keys (=bitcoin addresses), however, you will not be able to reconstruct the whole wallet file.