I size preflop a touch bigger than "standard" but I think its perfectly fine because they call horribly here and we are slightly deeper vs the CO. Also, if they have a monster, it will make their re-raise naturally larger are more committing.

Interested in your approach here. Obviously we have a few options on how to proceed a) bet smallish (not so great IMO) b) bet 2/3 pot+ (better but still gives a flushes a chance to get away on river when they miss turns). Also, it becomes complicated what to do on a diamond river c) Jam or d) check (by far the worst option IMO).

I don't think we are ever much better than 54 to 58% equity favorites. I think he calls all AJ, probably all KJ (4 combos) and he has 6 set combos. I would also expect them to call all Axdd and all diamond/diamond combo draws.