Hi,
I don't think you're going to get much success on this as some of the messages are generated by the kernel itself (hardware related stuff you'll find in /var/log/dmesg). There was a discussion in the linux kernel mailing list some time ago about suppressing these in future kernel releases but I don't think it was agreed.
After that stage, the '/etc/rc.d/sysinit' script runs then you get the 'Starting whatever [OK]' type messages which come from the sysv init scripts called via '/etc/rc.d/rc'. So you'd have to start changing the '/etc/rc.d/sysinit' and '/etc/rc.d/rc' scripts if you really want to suppress those messages.
Finally, /etc/rc.d/rc.local is called and that would readily allow you to change the default logon prompt - but only for runlevel 3 (console mode). If you go into a graphical X logon theres probably not much point.
Hope this helps