I would like some advice :)

Hi everybody
I am doing my research to start tinkering with an Arduino project and would like to ask a few questions.

I would like to start with a simple project that has a base plate with two motors below that can control the base plate around and up and down, it is not intended to go all the way around. I am still a little fussy on how the motors should be constructed to make this happen.

Heres a little demonstration:

There a few problems here, first off I'm have just started. Second I know nothing about Arduino. Thirdly the base should be able to carry up to 15 Kg. And off course, I have no idea what kind of motors would work and how to set them up, and what Arduino board and Shields I should be investigating.

Could anybody point me in the right direction so I can begin my journey into this most exciting world?
Any answer would be highly appreciated!

15Kg? Does that include the weight of the motors & batteries?
(~500g/lb, so 15,000g = 30 lb)

Could anybody point me in the right direction so I can begin my journey into this most exciting world?
Any answer would be highly appreciated!

What is the end product you are trying to develop? looks like a large pan/tilt unit. How fast does it need to move? will the motors be required to do any holding, or will they only provide movement force?