Hi Jordan, the payment schedule is up to you as long as there is a down payment when placing the order (at least 50 or 100 to start with). Postage can be paid whenever you’d like in any of the partial payments over time. Sorry I do not know about international taxes but the shipping costs are listed at the top of the “shop” page.
As noted earlier (and for everyone who is looking at down payments):
The way to do a down payment is to place an order for all the items you want and choose the “other payment” option. Then for your down payment, place a separate order for each deposit/payment using the store item “$1 increments” – most people are doing 50 or 100 at a time. https://www.modelfkeyboards.com/product/other-customizations-in-1-increments/
If you’re outside the US, for one of the down payments you’d pay shipping and for the rest of them you’d choose “free/other shipping” so you are not charged extra for shipping. Shipping is free within the US.