A few items to consider with offshore companies:
You will need to keep control of your offshore company. You make the rules, specify the requirements and monitor it. Monitoring will take place by performing regular audits to ensure the company is compliant with your policies. This could be patch policies, anti-virus, complex passwords, how they handle and store data, they are not allowed to use wireless and so on.
Demand for network isolation, all staff at the offshore should be on an isolated network dedicated for your work. I recently did a site audit of a offshore company for my company and noticed they had network separation in place but they had 6 engineers in the room, 3 working for us and 3 working for another company… cables where all over the floor and it seemed to me there was a lot of chance for confusion and compromise if one engineer would hook up to the other network. Also, they did not lock the doors when leaving the office at night and so on. Demand a dedicated work area with proper network isolation and make sure the work area is secured at night.
Of course there is much more to look at but figured I would throw in a thing or two.
-steven