それで

だからN4
だから gives cause-and-result more forcefully, often in assertions or commands, while それで is a softer, narrative way of linking cause to effect.
そこでN3
そこで introduces a new action taken in response to a situation and suits formal or written narration, whereas それで is more casual and simply connects reason to result.
で
それで is the full, slightly more formal form meaning 'because of that', while で is its casual, contracted equivalent used to link a reason to a result.
ですからN4
それで links a result to a preceding statement more neutrally, while ですから explicitly frames what follows as a logical conclusion.

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んで
んで is a casual, spoken contraction used to link clauses informally, while それで is the neutral, register-flexible equivalent usable in both casual and formal speech.
そのためN3
それで can simply prompt a listener to continue a story, whereas そのため explicitly marks a cause-and-effect relationship.
そしてN5
それで highlights a cause-and-result link ('so, because of that'), whereas そして is a neutral sequential connector.
するとN4
それで links events as 'and so' and can also imply a reason ('because of that'), whereas すると just marks the next event as a natural consequence without implying causation.

Politeness

そんでもって
それで is the neutral, standard-register conjunction meaning 'and so', while そんでもって is a casual, colloquial variant with the same function.

これで
これで marks a transition tied to something just done or present ('with this'), while それで links cause and effect meaning 'and so, then' referring to something already stated.

それでもN3
but still; even so; nevertheless
それではN4
well; right; now · so; then · if that is the case; in that case; that way · bye then

Compound of それ (that) and the particle で (indicating means or cause). The historical derivation is straightforward.