schedulers and compatibility options in 6.0-r

[Dave]

Hello,
    I've got a 6.0-RELEASE machine and am going to compile a new kernel on 
it.
I've got a few questions as to the best options. This is a single-processor 
machine, going to run only 6.0. Which of the schedulers should i use 
SCHED_4BSD or SCHED_ULE and do i need the PREEMPTION option? And the 
COMPAT_* options, 43, i know i need that, do i need the 4 or 5 options? And 
what purpose does device apic serve, do i need this? And is quota now used 
by default or do i have to compile it in?
    When booting this machine with GENERIC i'm getting some bootup messages 
i find slightly disturbing:

ahc0: (GIANT-LOCKED)
and a little later:
no suitable dump device was found
this is on a geom gmirrored system updated from 5.4-RELEASE-p6 to 
6.0-RELEASE.
    Thanks.
Dave.