1) Is it safe to always use the same wallet to send to BestMixer prior to mixing?  In other words, is there any privacy concerns if I always use the same "pre-mixed" BTC wallet address to send in my BTC to BestMixer?

2) I did my very first mix the other day and I selected the Gamma Pool.  I was supplied with a Best Mixer Code but I don't think I technically need it if I'm only mixing in the Gamma Pool.  Is that correct?