Hey there!
Well I don't think Canon or Nikon will be any different, really. DSLR cameras are just kind of complicated. But you will learn! We can give you very specific instructions for what you want to do with it. In the mean time, you can stick to auto or scene modes.
The K-x is a rather basic camera, buying a "higher end" model will only complicate things. The K-5 has more dials and buttons. And its no different if you buy Sony, Canon, Nikon, Olympus..
Anyway, for portraits, switch to Av mode, then dial the thumb wheel until the f number is lowest possible. ISO should be pretty low, too. Now get in close to your model and ta-da! The rest depends on the lens.
For macro, find the AF/MF switch on your camera (near the lens mount) and switch to MF - manual focus. Now look through the viewfinder and twist the focus ring in one direction and the other (do
not twist the focus ring if the switch is set to AF! Only lenses with quickshift feature allow that). One direction is focus at infinity (far away) and the other direction focuses near to you. Twist it a near to you as it goes. Keep the focus ring there! Now aim at the object and simply move in closer with the camera until it gets in-focus. How close? Depends on the lens (on it minimum focus distance, you can find it
here) For macro, you will probably need a tripod or something to keep the camera steady. Choose Av mode and select f-number between f5.6 and f14 for macro photos. The higher the F-number, the bigger the depth of field (the area that appears to be in-focus on the photo). You always get the highest magnification at the minimum focus distance. But non-macro lenses have a pretty far MFD, so their magnification is low. A macro lens allows you to focus very very near to the lens, which gives a high magnification. It is usually called macro when the magnification is 1:2 or greater, up to 1:1.