Congress people are voted on every 2 years. The Congressional election is the same day as the Presidential election. Lee won her primary to run for the seat again. Her opponent was Amanda Edwards, a former Lee intern. The republican winner in the primary was Lana Centonze. So I’d say this Edwards woman will probably be running against Centonze.
Depends on the state. Here in MO our local Congressman died a few months before Election Day. The governor (different sate laws may differ) held two elections on Election Day. One to fill the remainder of his term and another for the next term. The Congressman’s widow (Mrs. Emerson) won both.