Can we define items under Root item class and then later moved to specific classes

Setup of CX products

We are setting up Cx Sales and Service only for business, no SCM process will be setup in Fusion. For Product setup prerequisites are configured, however business earlier has gone with Root Item class and Root Catalog as the only setup.

1. Do we need specific Root catalog created Service, can we use the Sales Catalog directly, is there an impact or we loose any functionality by not setting up Service Catalog specific for Service functions.
2. If we create items directly under Root item class, as user defined naming convention, can we move the items later to specific item class. Is this possible. Or advise is to get the new Finish Good Item class created and create the Service items. Please let me know.