The Pro does not come with any programs other than those included with Windows 8 Pro operating system. Applications are downloaded from the Microsoft Store, free and paid. The Surface Pro tablet is just like any desktop computer, you can run any Windows compatible programs you like.
I like that it doesn't come with a lot of bloat ware like some tablets/laptops do. It just comes with the basic apps that come with windows 8. It also has a trial of office 2013. There should be no reason why you cant remove it and put a different version of office though. I personally love office 2013 though
I just looked at the Add/Remove Programs panel and it says that the MS Office that's installed is only ~300mb of space. I thought it would be more significant than that, so I think I'll just leave it there in case I want it later.
Mostly I've been using the web versions of the office apps lately.