1) Please confirm that there is nothing wrong with using the same wallet address for multiple transactions.
No, you can send coins to the same address as many times as you want, but generally it is advised to create a different receiving address each time for increased privacy.
2) Other than opening a ticket like I have, what other resources do I have?
Well, you could post here the tx id for us to help you better since we would know what we are looking at exactly.
3) Is it as all unusual for a transaction to confirm like this, but not appear?
If the transaction is seen as confirmed on all block explorers, and it doesn't show up in a place where you cannot control the private keys (all exchanges, ICO deposits, etc) and you are sure that you sent the coins to the public address used as a deposit address on there, then the fault is on their end since they control the keys. Contact customer support.