Moggie,
Tire flex will contribute to heat accumulation during an RTO, but I do not have the numbers or formulae to properly apportion or even guess the heat build-up components.
Yes, something less than full reverse thrust may be useable from an asymmetric engine depending on the factors you have mentioned. I plead guilty to trying to explain too much too consisely.
In the Gimli Glider incident where an Air Canada 767 ran out of fuel, the nosewheel collapsed. The passengers who evacuated the rear doors also suffered severe injuries from a near vertical drop to the tarmac. So yes by all means, evacuate by the lower exits when one end has come down to the ground unless there's a fire in the way.