Re CDs,there is a difference between brokered CDs which places like Fidelity and Schwab offer and a regular CD offered by brick and mortar banks.
At Fidelity, you can sell CDs but the market is not very liquid and you will take a substantial haircut. With a brick and mortar CD you often lose some interest if you break it early, perhaps three months. It is cheaper to break a CD with most brick and mortar banks. I think online banks that offer their own CDs such as Ally and Cap1 have penalties similar to the brick and mortar banks.
Ay Fidelity you can buy either call protected or non-call protected CDs. It is far better to by call protected brokered CDs, especially for long durations, which means the bank does not have the right to return your money early.
Now you're not going to want to break a 1 month CD and most likely not a 3 month CD, But 5 years is a long time to tie up your money in an instrument that's not easy to break in a cost effective manner. So (except for the current debt ceiling crisis) Treasuries are a better alternative in which the Bid-Ask spread is reasonably tight. But money market funds at Fidelity are paying a good rate too. 4.9% with a minimum 10K purchase in an IRA (100K if not in an IRA).