No, checkout is a simple one-time guest form asking only for shipping and payment details.
Standard orders are one-time purchases. Any subscription option would need to be clearly selected at checkout rather than applied automatically.
Yes, though delivery takes longer and international customers may be responsible for customs duties separate from the listed price.
A single jar works for testing it out, but since results build over weeks, most buyers choose the three or six-jar bundle to match the realistic usage window.