"We will still be eating" suggests that you will be eating past a certain time. For example, there's so much food, you'll still be eating at 8 p.m. or you'll still be eating when someone who has to leave gets back. "We will continue to eat" means we are not going to stop eating despite whatever happened.
Not sure I get it: I thought weiterhin was indicating the next activity (following the current), not a continuation of the current activity? If this is right, should Wir werden weiterhin essen not be "We will thereafter/then/in addition eat"? DL gives "We are going to continue eating" which indicates that they are currently eating. Help please.