Hello,
There are no silly qustion here, and your question allow us to give a good advice.
First, yes you can update to 4.4 from 4.0, now here, the advice, despite all our efforts, we cannot guarantee that there will be no adjustments to be made after an update.
There are many and many different ways to config, use and custom HikaShop...
And that's why, we always recommend to use a clone of your website to perform on it the update, and process some tests in order to check that that nothing has caused upheaval or hieratic events.
Hope this will answer you.
Regards