Congratulations on getting started with your new store!
The address you list for your business and where you register should typically be where you’re operating the business from, even if you’re mainly shipping to another region. Since you’re dropshipping, products might be shipped to customers from various locations, but the constant will be where you are located.
You can set up your Shopify store to calculate taxes automatically, under Settings > Taxes and duties. I recommend speaking with a tax professional in your area to determine the taxes your business might need to collect.