The Surface Pro is more powerful than the RT or Surface but its does only have an Intel iGPU meaning games will be limited in that way. It is also a tablet first with the idea of being a laptop second. It does not have a hinge to keep the screen up right like a laptop so works best with the keyboard attachment on a flat surface like a table using the built in kick stand.
It can be used like a normal laptop just not in every way.
The BIOS is pretty normal but not as robust as something from say Asus or MSI, especially their higher end models.
The Surface Pro is a full x86-64 machine with normal Windows 10 on it so it should run all the same applications as a normal laptop or desktop.
Yes. As said its basically the same as a normal laptop just with Tablet functionality in mind. If you want a laptop that has some tablet ideas you would go for the Surface Book which is a laptop with the ability to detach from the base and act as a tablet.