1. no. the sump in a beams is front sump, though it is offset even further forward. the car the engine is out of, is usually a front sump 6 cylinder. what this means is, depending on how far back you mount the engine, the sump may hit the sway bar.
basically, you have to wait till you install the engine, and which compromises you will make re engine position. you will need to either space the x member, get a new custom sway bar made, or enlarge the tunnel.
2. output is the same a w
3. factory headers and secondaries will be fine, if supplied.
4. the ex' is on the passenger side. there are no issues with steering.
5. get one big enough to cool it. camry/celica/whatever
6. you will need someone to wire it. at this stage i am only aware of 2 ecu's that can run the engine. adaptronic and motec.
7. no, just a normal set up will be fine. standard the altezza has the FPR in the tank like a lot of modern engines, so you will have to add one at the rail. no biggie.
expect the conversion to cost at least the price of the engine/GB package.
the main issue you havent mentioned is clutch and brake master cylinder clearance. youll need to mod both and/or the intake manifold.