My understand of the pool even if you don't fine shares you can still find a block? So regardless if you submit shares or not it makes no difference since you're not sharing the block reward with a community of miners
NO! If you are trying to use say a Nerdminer (70kHs) and never are able to submit a share because it is too slow, there is no way you can 'find a block'. Shares are proof that you have a valid miner that is doing work.