2. Does cgminer takes that into consideration when pointed to solo.ckpool ?
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5. Maximum nonce on 32 bit is 4294967295. That's ~4.2 Gh/s. When you have more hashing rate than this does what mining software (cgminer in particular) does in meantime its waiting for next work ?
2. Accepted shares can be a lower difficulty than the network diff, and just show you (and the mining software) that it's working
5. You can change the time, or the extra nonce. You can also get fancy with adjusting the merkle root. Mining space is practically unlimited.