You can just use an individual exchange wallet for all the six coins you plan to purchase. Now in case you decided to follow that advice, I recommend you use Bittrex as all the coins you mentioned are available there. Additionally, you can also use MyEtherWallet, though if you do not have ETH in your account, you cannot send them back to an exchange platform because you will be needing gas to do that. With regards to the coins, IMO, better to just stick with BTC at the moment and just buy them when you see a dip.