Standard IQ tests tend not to test memory. It is true some knowledge is required for parts of the tests but memory is not the dominant component being tested. It is more about the speed at which you can reach conclusions to a long set of short tests, e.g. pattern recognition, sequences, math, and logic problems. Most people given enough time can complete all the questions in an IQ test, they are generally not hard. The test is how fast can you do them.
An example would be comparing a 20 year old computer with the latest, they both complete the tests, but the latest does it a thousand or more times faster. It would seem that people's brain's also operate at different speeds.
Unfortunately it is possible to cheat somewhat on IQ tests by practicing the types of tests that are typically presented at the formal tests.
As for artistic talent: I would say that such human abilities are independent of intelligence. IQ tests simply do not measure such things.