1) b)
As for the example sentence, ゆっくり食事を取って is used for continuous usage, thus, the nominalizer こと is the key.
The etymology of the particle で and the -te form of だ are the same. Or rather, some usages of で are treated as a conjugation of the copula. So, your confusion is understandable.
2)
Yes, that's 来そう.
The meaning depends on the context, i.e., what そこ refers to. It also can mean "we can retrieve those scenes (through slow food)".