I'm hoping to get to Port Isaac and Tintagel Castle. Where should I stay in the area in order to take public transportation into and out of these two locations?
As regards direct buses- the #96 goes from Bodmin to Wadebridge via Camelford and Port Isaac.
The #95 goes from Bude to Wadebridge via Tintagel and Camelford.
The common theme here is Wadebridge and Camelford.
Of those two I would choose Wadebridge any day- quite a nice small town on the banks of the River Camel. From the rail network the most usual access point is Bodmin Parkway station with a half hourly bus #11 from there. Every other #11 extends on to the port town of Padstow, and every 2 hours the #11 starts back from Plymouth before calling at Bodmin.
Stuart (isn31c) knows his buses. If you decide on Wadebridge, here are a couple of sites you might want to check oout:
https://www.visitcornwall.com/destinations/wadebridge
https://www.stayincornwall.co.uk/handbook/locals-guide-wadebridge
Also, here is a link that will let you review some threads from the last 2 years that have some mention of Wadebridge
https://search.ricksteves.com/?button=&date_range=2y&filter=Travel+Forum&query=wadebridge&utf8=%E2%9C%93