Multiple issues (FreeBSD 6.2 RELEASE)

[Lucas (a.k.a T-Bird or bsdfan3)]

Hardware: Compaq Presario 1200-XL118
AMD K6-2 500MHz
64MB of RAM
Trident CyberBlade i7 video with 4MB shared RAM
6GB ATA66 HD
Linksys 10/100 PCCard Ethernet (using ed driver)

OS: FreeBSD 6.2-RELEASE using GENERIC kernel

Issues:
1) The machine will not turn off when I try to soft-off it (ACPI S5 
state, shutdown -r or -p).  How do I fix this?
2) X gives me errors about not being able to open /dev/mem and /dev/io 
such as "Operation not allowed".  This occurs both when X is started 
directly as root and from xdm run from /etc/ttys.  Again, how do I fix this?
3) Does anyone know if this machine supports S4BIOS?  It lists S4 as a 
supported sleep state, but the hw.acpi.s4bios sysctl prints as 0.
4) How do you set sysctl tunables at boot time?

Please CC me, as I am not subscribed to the list.