Thank you Klynn for your pictures!
Very nice ones.
I would renew my recommendation for an APS-C camera. The advantages of a FF camera do not outweight the additional weight you have to carry.
Concerning K-3 (i or ii) against the KP, they are both very capable cameras. The K-3 is the more rugged one, with the flagship ergonomics, i.e. a knob for every function. The KP the more modern camera with a tad better IQ. The one big advantage that the KP has over the K-3 ist the tiltable screen, which makes low level pictures like the one of the lying black dog possible whereas it is not as easy to take those pictures with the K-3.
I would also like to suggest you take into account the K-70, which has an fully articulated screen and very good image quality and is in my opinion quite comparable to the KP in terms of user interface. It's main issue is the elder AF-system.
Pentax KP Review - Specifications | PentaxForums.com Reviews
In fact I would base my descision on which lens is bundled with the camera. If you can get a 16-85 or a zoom lens with f2.8 that would be nice. A 18-135 is an excellent lens up to 50 mm and gets meh at 135, but I own one as a walk around and it is ok. Add a DA 50/1.8 for portrait and you will be fine for the first steps.
Yo wrote you want a macro for taking picture of canavas paintigs. If you do only want to reproduce the whole painting and do not want to do detail enlargements, you do not need a dedicated macro, but only a lens with minimum distortion and field curvature. The DA 50mm/1.8 and even the 16-85 at 50 mm will propably do.
Please note, that if you like to reproduce a whole middle sized canvas (80cm hight) picture anything longer then 50 mm will require you to step back a bit more.
That said macro from 70 mm (Sigma) to 100 mm with f2.8 is a nice portrait lens as well.
Here my suggestion is to start with a good standard zoom (16-85, 16/17-45/50, 17-70) or something like this, then use it some time and decide afterwards which additional lens you need.
You can allways ask for advice here in the forum, especially for lenses you will get a lot recommendations
.