Hello Roland and firstly welcome to the world of roboteering
Your questions are sound ones and we and i speak for all roboteers on this forum and in our community are very pleased to see new blood coming into our spobby ( sport / hobby) = spobby your questions will be answered from all over with different opinions from different roboteers and can take you in all sorts of wierd and wonderfull roads.
I for one will give you mine ,,,,,

1) First and formost design your robot draw it make it out of cardbord and tape ect but get into your mind what you want to make .

2) Tools : basic hand tools screwdrivers ,pliers,wire cutters,hacksaw,spanners,soldering iron, Oh and a HAMMER...

3) Where from ,,, car boots cheap tool shops ect..

4) Internals two cheap cordless drills will give you drive and speed controllers are available from most modelshops and online on this forum :: For sale thread, with the drills you get free batteries too ..

5) And on that note i will stop for now and give others a chance ...

6) Check out Roaming Robots online shop I know johnno sell the rat kits which is a good way to get into our spobby ..

Pete