Just wanting to check if we obtain an SSL certificate for our domain, if we are able to use CB Subs plugins to accept credit card payments directly on our website without having to direct our community away to Paypal or whatever processor we are using.
You need to be completely PCI compliant to accept payments onsite. This includes an SSL certificate, yes. See the below for details regarding PCI compliance.
www.pcisecuritystandards.org/
If so, which is the best processor to use in your experience?
I, personally, recommend Stripe.