Re: Adding more RAM - yes, a computer store could do this, but it's a bit more annoying on the 10v than the 9 in that the motherboard has to be removed, which a store may not be willing to do. 1GB is probably adequate for your purposes.
Re: Windows programs - did you order it with Windows or Linux? If Windows, then it will, of course, run Windows programs. With Linux, many Windows programs can run if you install software called Wine.
Mac OS X is not supported by Dell. Experienced and adventuresome users can and have installed OS X on the Mini 10v - if you feel you're up to it, that's great, but it may not be as easy as it looks from watching a video. It is also possible to run Windows programs under OS X - there are a few different ways to do it. I'm not an OS X user myself, so I would suggest you follow up on that question in the Mac OS section of the forum.