for the second question again takin my operating system into consideration;
when i upgrade my system using yum, i so that in /boot folder there are 2 new kernels apart from the old ones.
names are listed below :

core-2.4.22-1.2115.nptl
core-up-2.4.22-1.2115.nptl
core-2.4.22-1.2115.nptlsmp
core- 2.4.22-1.2115.nptlsmp

.

in my opinion : just select one and always use the same :p
not a professionel explanation but i've been doing this for some time and nothings wrong with system.
Regards.
Bye