New to Modelling/Retexturing - How Will I Go About This Particular Task?

[CosmicDwarf 10]

I'm sorry if I've posted in the wrong forum, but I wasn't sure about who to approach or indeed how to approach this issue in general. Sorry about the vague title as well, I wasn't sure how to phrase this question succinctly enough - don't worry, I am not asking for a tutorial necessarily, this is a specific issue I'm unsure of how to approach.

I've been trying to use this official BIStudio-created Arma 3 uniform in one of my missions (it's from the main campaign in single player):

Unfortunately, there are problems with it. The main one being that the uniform's arms seem to override those of the wearer, forcing them to have Mediterranean, olive-skinned, tattooed arms below the elbows even if the player or unit is black. It's disappointing considering you don't tend to experience that with the various polo-shirt uniforms in game. Here is a screenshot I took a few minutes ago showing the problem:

http://i.imgur.com/0HMfYCU.jpg (387 kB)

The second problem is that, while wearing the uniform, the player cannot actually see any guns in his hands. Guns become invisible, forcing the player to play in third-person. I assume this has something to do with the blasted arm-override thing?

Normally I'd just let this slide and try and pick a different uniform. However I really like the way this uniform works for my mission, and this time I'd rather just fix the problem. I'm sure I can learn some skills along the way too, which will undoubtedly come in handy at some point in the future.

Now, my understanding (limited, I'm afraid) is that this is either going to require re-modeling or re-texturing the uniform. I don't know which, though, as I don't know how this strange arm-override works. Is this a matter of a texture or a model? If it's just a textural problem, why does it make my gun invisible?

If anyone would be kind enough to point me in the right direction (i.e. what I'm going to need to do to get what I want, what program I should use etc) I should be able to find my way from there. There's loads of tutorials around so I'm sure I can find them. Thanks.