What happens to feature properties (attributes)?

They are dropped - WKT stores geometry only. This is normal for pasting into a SQL WHERE/INSERT using ST_GeomFromText().

How are multiple features written?

As multiple WKT lines, one geometry per line, in the same order as the input features.

Convert GeoJSON geometry to WKT (Well-Known Text), in your browser.

Input (GeoJSON)

Output (WKT)

POINT (-122.4194 37.7749)

Runs entirely in your browser - nothing is sent to a server.

What happens to feature properties (attributes)?: They are dropped - WKT stores geometry only. This is normal for pasting into a SQL WHERE/INSERT using ST_GeomFromText().
How are multiple features written?: As multiple WKT lines, one geometry per line, in the same order as the input features.