login as root and type in top. There you'll see your load, mem usage and all that kind of stuff. Fire it up in the prime time and check if the load stays allright.
A simple way to check uptime is to use the "uptime" or "top" command. Depends on your account you might want to login a casual user or root.
Uptime is basically the number of active processes running at 1, 5 and 15 minutes, respectively.
For processes, use "ps" or "pstree" to see a list of threaded processes.
Install MRTG or rrdtools and feed data to them to create nice and customized graphs of the entire system.
For database, I know MySQL is able to handle a high number of queries per second. The two most common bottleneck are disks and memory. So they are somewhat related to system load.
The rule of thumb is if your system constantly reporting a load average of 3.0 or more, you are running out of resources.
How to measure and monitor load?
