taking photos of fine art

as an artist who paints portraits i need a camera with the following capabilities:

• accurate reproduction of paintings/drawings

• quick and responsive to take portrait photos which i can use as basis for drawing from (with good natural colours)

• quick play back with responsive zoom so can quickly check expressions etc, ideally being able to scroll through images at same zoom point (like canon)

• good low light performance for interior group portrait shots

• quality lens of approx 28-105 (film equiv)

have had very disappointing results with d20 (perhaps faulty camera??)- dirty and unsharp images, vastly inferior to g5, although liked the playback facilities.
liked d70 images but found playback navigation very lethargic.

abandoned old eos 500 several years ago and till now have been using G5 which has given pretty good results but is very slow.

is there a camera out there which can do it all??? or am i asking the impossible???

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rosanna