The gear actually isn't as important in your situation as the workflow to preserve color accuracy. The main issues you'll need to consider are:

1. Accurate white balancing when shooting. This typically involves shooting in RAW format (so you need a camera that shoots in RAW) with some type of color reference in the frame--something like a WhiBal or ColorChecker--and then using that to white balance off in post, typically using an eyedropper sampling tool to set a white or gray point. If absolute-spot-on color accuracy is not required, but only good-enough-to-eyeball matching (i.e., to avoid having heavy orange cast from tungsten/incandescent lighting, blue from flash, or green from flourescent), this might be enough without a lot of additional outlay.

2. If it has to be spot-on, however, then you need accurate color calibration of your camera, your monitor, and your printer. This will probably require specialized hardware and/or software, and there is no getting around that. At each stage along the way, how the colors are represented internally can be out of calibration with the other two. So you need to make sure that each is accurately calibrated or profiled in a way that ensures you consistent and accurate color representation. To do this, you are most likely to need:

   • A color reference card
   • Software to turn shots of the color reference card into a camera profile you can use in your post processing package of choice.
   • Monitor calibration hardware--something that can sense the color coming from your monitor
   • Monitor calibration software that can take the hardware readings and adjust the settings on your monitor based on them.
   • Printer/paper combination ICC profiles (can come from the manufacturers of the printer, paper, or inks when you purchase from them or download from their websites).

Note how nothing on that lists indicates a specific camera or sensor type. Color accuracy has little to do with the sensor hardware these days, since all of them are pretty good, and variants such as Foveon or X-Trans sensors, while they do give you some advantages, must still go through this same workflow to ensure color accuracy.

For shooting paintings and closeups of paintings, however, you're most likely to be happier with a camera or camera/lens combination that can provide you the following things:

• Full Manual mode, for exposure control over iso, aperture, and shutter speed.
• RAW capability
• macro capability [may require a separate lens with an interchangeable-lens camera]
• Some way to use off-camera flash (typically a flash hotshoe)
• A tripod mount hole
• A cable release port

Shooting paintings typically involves controlling reflections and showing texture by controlling and/or diffusing the lighting, shooting details typically involves shooting close-up, and you may need to be able to shoot in lower light or from specific angles, so using a tripod and cable release can come in handy.

See also: http://news.smugmug.com/2014/05/14/the-art-of-copy-work-photographing-artwork-accurately-without-glare/