[happycamper]

I'd suggest using a paint marker to put a line across the belt and each pulley before removing the belt.
Then lay the old belt next to the new one and copy the marks to the new belt. You may need to count the number of cogs on the belt between marks. This is a good way to double check everything.

 

[happycamper]

Buy a good set of sockets instead of an electric driver. You should have a 10mm socket with 1/4", 3/8" and possibly 1/2" drives.

You should also have ratchets with long handles which gives additional leverage. I like the ones that swivel, which helps in tight locations.
Something like this:

1/2 in. Drive Professional Long Reach Flex Head Ratchet with Comfort Grip

Also, you might have better luck using a combination wrench instead of a ratchet in that situation. Ratcheting ones would be even better...

 

[happycamper]

You are using the correct setup for the crank bolt.
I have (carefully) stood on the end of a six foot cheater bar to break these loose. I weigh around 150 lbs, so that is around 900 ft lbs of torque.
Make sure you have a good breaker bar and a high quality six-point socket

 

[happycamper]

I would strongly discourage using the starter bump method. You don't want to add a new flywheel to your timing belt project.

 

[happycamper]

The valve springs have enough force to push the cam to a "happy" position. So, it isn't uncommon for the cam to move slightly when the belt is removed.
Keep in mind that the crankshaft rotates twice for every rotation of the camshaft. The new belt could be installed correctly to the marks, but 180 degrees out of phase.
So, be careful and think about what you are doing. You don't want to start randomly rotating camshafts.

Hopefully you marked the old and new camshafts with paint marker. this will make it much easier to get everything correct when the valve springs are trying to rotate the cams out of position.