> - What is the difference between page_read and page_fetch?

page_read is when page read from disk, i.e. cache miss.

page_fetch is when page found in cache, i.e. cache hit

> - What is page_mark?

someone have intention to change page contents

> - What is record_backout?

undoing of not needed primary record version. it can be in case of
transaction rollback or undo of savepoint if some statement under this savepoint
is failed

> - What is record_purge?

remove chain of unneded record versions, leaving primary record version
(and may be few backversions) on it place as it was created by transaction with
number not less than OAT

> - What is record_expunge?

remove whole record versions chain as record was deleted by transaction
with number less than OAT

> - Is it possible to know the execution plan of a statement?
> - Is it possible to know the values of parameters passed to a statement?

No

Regards,
Vlad