Dude, relax. I didn't have an IRD Crankset hanging on my wall at home and needed to wait until I came to the shop and look.

The back of the chainring has slightly recessed bolt holes. Not sure if there's enough for the serrated bolts to grab.

Any 110mm JIS BB will work with Defiants.

The dust caps on Royal Nuevos can be removed using the Park SPA-2.

The Rush fork uses a 26.4 crown race so you should be good to go with the Levin NJS.