1) Bandwidth: If the 1Mbps plan and the 5Mbps plan are both uncapped switching between them wont make a difference in terms of download speeds for end users.
2) Loads / CPU: Loads indicate how many processes are waiting to use the CPU, anything below one is great. If its above that, then alot of factors come into play such as how many logical CPUs and whats cause heavy CPU utilization. With your loads your CPUs are fine.
3) RAM / Swap: If you run the top command you can see how much of your RAM is in use. Depending on the OS it may appear that all of it is in use even if it isnt. Whats more important is to make sure you arent using swap. No swap = no need to upgrade ram. Small swap usage <100MB is usually fine, anything above that and its time to consider upgrading depending on how your site performs.
4) If everything is configured and optimized you dont need to make any hardware changes your surfers should already be getting maximum throughput. If things aren't tuned then obviously you can squeeze out some more performance and make things faster for them.
If you have any questions hit me up on icq at 36837470.
