Does anyone know if there is a definitive list of bitcoin exchanges and wallets that are going to be distributing bitcoincash? 
What distribution? It's already over even If you add bitcoins into exchanges right now, you won't be credited BCH and If you are looking for exchanges that accept deposits with low amount of confirmation then I suggest HitBTC, and for a full list check CoinMarketCap as BitcoinCash official site seem to be outdated.
Not so! Coinbase is planning to credit BTC holders with BCH in the near-ish future. As long as the BTC was there pre-fork.
Same with BitPay Exchange.