So I'm not saying that we should stop transacting with them, but just do the necessary steps to protect yourself like take screenshots for reference. After all, there's no other exchange for psb just yet with higher trading volumes other than CCEx and Novaexchange. I'm not a fan of Yobit. Sorry.
Ok safety always first; keep tabs on your txids, don't leave coin at any exchange. Other than that, C-Cex is pretty much the same as all the other exchanges I know of. It's all internal transactions.
These BTC movements are normal - the case is nobody should leave BTC or PSB at the exchange once the transaction has been made anyways - just withdraw everything, and stake!