I always encourage people to build kits if they are willing, since it is such a good learning experience and gives you the ability to fix the printer yourself when things go wrong. It is also by far the most economical way to get into 3D printing. You can get a kit for roughly half the cost of an equivalent preassembled machine.

I've never dealt with the HICTOP or Alunar kits, but they are all based on the Prusa i3, which is probably the most popular 3d printer out there. This means it will be very easy to get help and find replacement or upgrade parts. We sell an i3 kit made by BQ, which I like because it comes with very good instructions.

Unless a kit specifically says it has an all metal hot end, it probably doesn't. Your ability to print different materials will by limited by the maximum temperature of your hot end. I wouldn't worry too much about HIPS, though, since it prints at the same temperatures as ABS.

Most printers are capable of 100 micron layers (0.1 mm) but we normally print at 200 microns (0.2 mm).