Personally, being new to the website business, I think you should start small.
Build the brand, establish an identity, have a small shop where Customers can request orders, but don't process them online, process them through your current known to work methods that you have relied on for the past 20 years. Yes, that means there isn't an instantaneous result, but it does ensure you won't promise something you can't do and helps avoid any glitches that may arise from a fully built web site.
Take it slow. No need to hurry if the business is already making money. You have plenty of time and years to add more features to the web site, but do it based on customer request, not on what you think you need.