swing arm crack

it happened due to chain slipping off and locking the back wheel and catapulting me abt a dozen feet. now ik when it comes to chains it’s all abt how good u take care of them however i’m starting to think it my wheel. because i recently had a 600rim and tire i had me 929 hub on a 600rim rode that for about three months never noticed any wear and tear on the sprocket and really only had to tighten the chain i think twice. how the tire on the 600 rim started showing bands so i finally bought a tire for my 929 rim that was abt a month ago
since then my sprocket has worn so bad it looks like a shrunken the teeth are so bad i could
use it as a saw blade.
oh yea i for got to mention i bought the bike last year around may and i’ve had to replace the sprocket and chain 4 times!
is this just the normal lifespan of chains and sprockets?
also how should i go abt the crack in the swing arm weld it? replace it? don’t worry abt it?

 

Something is different with 600 wheel compared to 929 wheel. Spacers, sprocket-carrier offset, etc.
Which year/model 600 wheel? There's difference between CBR600F4/F4i rear wheel vs. '03-06 CBR600RR and '07-12 CBR600RR wheels vs. '13+ CBR600RR wheels.

929rr = 530 chain & sprockets
600rr = 525 chain & sprockets

Do you have completely different set of sprockets & chains for each wheel? How often did you clean & oil chain?

Post some photos of worn sprocket & chain from 600 and 929 wheel. Might show some kind of misalignment.

 

When you say crack do you mean the spot in the mddle where the two pieces meet? I'd take it to a welder and ge their opinioin but it looks like a good cleaning and reweld would fix that just fine.