Can my client see the buy rate, sell rate, or the commission I am earning on their deal?

No. Financing details like buy rate, sell rate and your commission are team-only, so they never appear in your client's view. When you add a client to a deal they get a limited portal: an overview of the deal and the application side, which is what they need to answer open questions and upload documents. Adding the client to a deal is optional as well. Some brokers run everything white-glove and keep the client out of the portal entirely, others bring them in because it speeds up document collection. Either way the economics of the deal stay on your side.