Additional Questions
1.Are There Any Minimum CPU requirement For Running Node?
I don't remember ever reading about a certain CPU requirement for running a node so I assume it will work on most of the CPUs that came out in the last 10-15 years. You need at least 2-4 GB or RAM and plenty of free disk space.
2.Is Prune Node Contributing To The Network?
This was explained by luke-jr here:
https://www.reddit.com/r/Bitcoin/comments/9ztepo/does_running_a_5gb_prune_node_support_the_network/Pruned nodes contribute basically just as much as non-pruned nodes, so long as you use it.
The primary way in which nodes help the network, is by the node operator using it to accept payments, and only honouring those payments after his own node shows the transactions confirm.
Whether the node is listening or not, or archive vs pruned, is irrelevant to this primary benefit. Overall network security depends on a super-majority of economic activity being received in this way, so it is important that as many people as possible do so.
The benefits provided uniquely by listening and archive nodes is a "just need enough" type thing, and (unlike the security aspect just described) can be provided by datacentres. The network has far more of these nodes than it needs already, so the individual contribution of one is basically irrelevant in the big picture. That is, relaying blocks and transactions isn't really important.