Lincoln understood that he was skating on the edge of the law. Under Article I, Congress, not the president, can revoke
habeus corpus. Congress was not in session at the time, so Lincoln made the call on his own. When the new Congress elected in 1860 finally took office, that Congress approved every decision Lincoln made under the emergency generated by his invocation of the Insurrection Act of 1807 after the unpleasantness at Fort Sumter.
Concerning arresting members of Congress, Rep. Clement Vallandingham of Ohio was expelled by the House for his support of secession. He wasn't imprisoned.
Well, much as I love the thought of a brigade of Marines double-timing up the steps with weapons at port arms, I’m back to hoping the leaders of the plot will get rousted out by declas and prosecution for documented crimes against the state.
I do feel time is running short.