Why does GA4 show fewer conversions than my orders actually were?

Ad blockers, cookie consent declines and cross-device journeys all cause some under-counting - treat the number as a strong trend indicator, not an exact total.

Do I need a separate conversion event for every action I care about?

Only for the ones that actually matter to the business - a purchase, a form submission, a call click. Tracking everything makes the reports harder to read, not more useful.