Oracle performance question for AWR reports

Below is an Oracle performance question for AWR reports from Oracle Specialists Community:

I got 2% physical reads in the field of Physical Reads/Total Read ( slide 8 ) from Oracle AWR reports.

1. Does it mean that 98% of reads came from Oracle SGA?
2. From Oracle perspective does physical read could be also reads from the cache of the DMX?
3. In such case, do you think VFcache is irrelevant?