there is one old article on metalink:
Note:3286.1 V6 Recovery - How It Works and Some Examples
It explains quite a lot, regadles of V6 of Oracle.

Disclaimer: what is said bellow could be wrong :-)
To question 1
ora-01207:file is more recent than controlfile - old controlfile

Looks like you tried to recover database with OLD control file. In that case you need to specify

recover [until cancel, etc] using backup controlfile

That 'backup controlfile' clause is only needed to allow database to pass sequence numbers recorded in control file.

To error:
ora-01194: file 1 needs more recovery to be consistent
ora-01110: '/app/oracle...../system01.dbf'

When I get this error while doing a recovery using "recover [until cancel, etc] using backup controlfile", the solution is to apply latest online redo log.
Then recover gives message "media recovery completed" and database opens with reset logs.
However I am amazed why it is that way, as all datafiles seems to be checkpointed at the same SCN before applying that latest online redo log.