@doobre Welcome to the forum!
That depends. For most day-to-day tasks and as a “normal user”, the browser extensions are sufficient.
The desktop app – at the moment – doesn’t have autofill capabilities (but the browser extensions have). The desktop app is needed if you want to use biometric unlock on the browser extensions and if you want to use SSH keys.
In the (hopefully near) future, the desktop app will also get native passkey support (on Win and Mac) and an auto-type feature (also an Win and Mac).
Which setup instructions are you referring to? Do you have a link (or screenshot)?
Yes, you can set up “Unlock with PIN”. If you uncheck the “Require master password on browser restart” option there, you can unlock with PIN directly when you open Brave browser.
If you already had set up unlock with PIN, it may be the case that you don’t see that option now. In that case, first disable PIN unlock again, and enable it afterwards. In that setup process, you should see that option again.
Be aware though, that unchecking this option reduces the security to a degree:
If you do mean changing the password on that site/service and in your BW vault, then unfortunately there is no automatic solution to change passwords on sites/services. (and that limitation is not exclusive to Bitwarden…)
The most recommended workflow is, to open the login item in BW parallel to changing the password on the site. That way you can generate a new password via BW, store that in the login item and drag & drop (or copy & paste) it into the “new password” field on the site.
Here a screenshot to illustrate that you can generate a new password in “Edit item” for login items:
(FYI, the last five “old” passwords in a login item do get stored in the password history of the login item)
Just to mention it: other options would be using the autosave prompts or the inline autofill menu/generator. But those have their own “quirks”…