For that part and for you to learn I’d say yes try it. From your brief description you have the basic concept.
On the other hand a fiberglass mold is fine as well.
The silicone mold will cost more and take longer to make but you will learn a lot.
Which way do you want to go?

To to answer your question yes you need mold release to protect the mold, release the part easier, and get in the habit of the process.