Check the BCD of your crank, if it's 110 5 bolt it's really easy to get a new narrow/wide ring for it, which will save you a good bit of cash and work as well as a new crank.

If you want to change the crank anyways Apex 1 is fine. You'll need GXP with a new GXP BB to go with it.

Your derailleur does not have a clutch. Lots of riders have good results with a narrow wide and a road derailleur, but depending on conditions you may need additional chain retention. A 42 with an 11-32 is pretty common 1x cross race gearing, but will be pretty rough for steeper for sustained road climbs, and bordering on unrideable for a lot of offroad uphill. That derailleur officially supports up to a 34t, and probably will shift a 11-36 pretty OK. If you want a wider range and/or a clutch you pretty much need to go with a full SRAM 1x drivetrain.