WordPress and WooCommerce are both very extensible. Similarly, WooCommerce Payments should work well with most stores and most other plugins. The documents below provide greater detail on some specific compatibility scenarios.
WooCommerce Payments is available to merchants in this list of countries. Provided your business is based in one of those countries, you can accept payments from customers located anywhere in the world.
WooCommerce Payments is built in partnership with Stripe. We also make a Stripe extension that integrates with regular Stripe accounts. As such, we have a document that explains the differences between the two solutions, as well as a page on how to use both, if you wish.
If you need to test whether an issue is being caused by your theme, you can install and activate our free Storefront theme. Storefront works perfectly with WooCommerce Payments. Thus, if the issue does not occur while using Storefront, your original theme is likely to be the cause.