From what I gather, Steve moved to Los Angeles in early 1978, not long after Hobo with a Grin was completed. He returned to London at the end of the same year and began working on The Candidate album in early 1979.
Steve married in London - the excellent harleyfanzone.com did have a scanned collection of old cuttings, one of which from 1981 confirmed this.
Not sure on the second question, perhaps someone might have an answer?