https://www.law.cornell.edu/uscode/text/18/1001
18 USC 1001
Felony, yes, but see the narrow category of false statements that apply when giving testimony to the legislative branch - 18 USC 1001 (c)(2)
Ignorant. Legislators are never impeached. They are removed (by the body) under rules, regulations and procedures totally under the control of the body.
There may be Steele transcripts associated with defamation case in UK or US.
https://www.reuters.com/article/us-britain-court-steele/london-court-rules-uk-spy-behind-trump-dossier-must-give-evidence-in-u-s-libel-trial-idUSKCN1GS2L2