Hi @AN2323
These are all great questions and I can definitely understand why it is so important to figure out before going live with your business. Hopefully, I can share some information that will make this decision a bit easier for you.
I was wondering if it is possible to expand into international markets too, like Canada and USA.
Yes, it is absolutely possible to expand your markets from one store, located in one country, to many others. All Shopify stores have the ability to sell internationally, regardless of where the business is located. If you want to sell and ship products to Canada and the USA, you can do that with no additional setup required, other than having the shipping rate setup for those countries.
Will I be able to run Google Ads and Analytics in the Canadian and US markets without a problem?
Google does offer the ability to run targeted ad campaigns, but each country may have its own rules and requirements for that (store language, checkout currency, listed prices). You can learn more about how to run targeted ad campaigns in the Google Help Center: Target ads to geographic locations - Google Ads Help.
Will there be issues with the currency my clients use to pay?
Issues with currency depend on what currency you wish to use on your store as the primary currency. As well as what payment gateway you want to use. For example, if you want to use PayPal express checkout on your store (very popular) your store currency will need to be in USD and you will not be able to accept payment through PayPal in INR.
Learn more here: PayPal Express Checkout for India · Shopify Help Center
And here: Payment Gateway India - Simple Credit Card Processing Setup - Shopify
If I move my business to Canada permanently, can I set that as my default country and CAD as the default currency my customers pay in?
You can do that, so long as you are able to provide evidence to your selected payment gateway that you are an established business in that country. Moving the registered business country though is not required to change the default currency on the store. Regardless of where your business is located, you have full control over the store currency and which ones you make available to your customers.
To aid all businesses using our platform we recently rolled out a feature called Shopify Markets, and it is available to all merchants as soon as they sign up. Markets allows you to setup regionalization so that customers from different countries can see products in their preferred language, currency and with customized shipping rates to suit your business needs. You can learn more about Markets in our Help Center here: Managing markets · Shopify Help Center.