@HossamL01,
Yes, you should be good to use vSAN licenses on Essentials Plus licensed ESXi hosts (provided you have valid vSAN licensing applied to the cluster).
Please be informed, vSphere Essentials Kit or vSphere Essentials Plus Kit licensing limits the number of hosts managed by vCenter Server Essentials to 3 Hosts.
Reference - https://blogs.vmware.com/vsphere/2018/10/vcenter-server-licensing-options.html
With regards to your 2nd questions, yes vSAN Enterprise Plus is licensed per CPU only. Please refer Page No.6 on below VMware vSAN & VMware vSAN+ Licensing, pricing and packaging guide.
https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/products/vsan/vmware-vsan-licensin...
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Regards,
Shen