What sort of pistons is he getting? I'd think he'd need something with a big D-shape bowl in it or a reverse dome to get the compression down.

longer rods will make the engine more "ping" resistant and let him run less overal ignition timing.

How do they do that?

the shorter pin to deck height will make a more stable piston and cut down on bore wear.

Bore wear has never been a problem with stock stroke & stock rods.

the longer rods will have less side load on the crank.

Not measurably.

I wouldn't be in any hurry to toss out the stock rods or stock crank, especially in the B30. Firstly, you can't reduce the size of the crankpin in a B30, like you can in a B20. Secondly, long rods don't help power at all until the cylinder head reaches it's limits in an NA motor, so increasing the rod ratio in a turbo motor is going to give away power under 3500 & never give it back because you just can't rev the B30 up that much without it bending.