Hi everyone! Have a quick question for you. Is this correct, as far as NetSuite is concerned, the Order to Cash process is this: (Estimate -> Sales Order -> Item Fulfillment -> Invoice -> Payment)

Yes. You can have opportunities but they are for internal use only.

Thanks @sam1128 anything else I've been missing? And is it ideal to follow this entire process, i.e. use all transaction types.

Process always depends on requirements. Opportunities and quotes normally exists if you’ve sales team selling things by phone. For E-Commerce sales and invoice is the only process I’ve worked on previously.