It depends on many factors. Are they willing to do it as a convertible note? If you're early stage the debt will be a burden if you don't have revenues in short order to repay it. 20% is extremely high and if you can't repay in revenues it could bankrupt you.

Investors outside the U.S. Are not weird at all, in fact often very smart investors. But you have to get to know them first.

In sum: how badly do you need the capital and do you think you can repay before it's due? If not you'll need to set repayment terms in case you don't hit your revenues. Just don't get stuck working to repay debt.

Even for Venture Debt, 20% is absurdly high, don't take it. If you have sufficient revenues to pay back a loan at a predatory rate like that, then you'll easily be able to raise capital via equity or at a much, much lower interest rate.

In a startup, I would only accept debt (unless is convertible debt) if you have significant revenues to pay off the debt with your current cash flow and are looking just for extra cash to invest in growth without getting diluted.

Considering you are at a seed stage, thus no (significant) revenue, I wouldn't accept this, specially if they are also requesting a collateral.

It really depends. I have worked with multi million dollar deals in the past. A $1M investment is a good find for a start-up however you will want to make sure you fully understand the terms. You will also want to fully understand if this is to be a 100% debt instrument, equity, partial equity, or a convertible note. Overseas investors are not necessarily bad, but you should be on guard if they ask you to pay funds upfront without any escrow protections. I'd be happy to discuss your situation in more detail on a consult.