Definitely not worth to get any of the pre-made desktop IMHO, you can always get a better parts and cheaper price if you build it yourself. Well, people buy it for a reason, just like people around me don't understand why want to spend so much for a gaming laptop when you can get a way more power desktop.

technically it can works if the size of the new board can fit into the z5 chasis, but consider you are going to change everything except for hdd only. new cpu, new gpu, new ram, etc.

You can disassemble the bottom case and take out the battery. It's not hard.

It won't void your warranty as long as you don't break anything. You can also send in to us for dust cleaning service