She won the no-confidence vote only because she agreed to step down before the 2022 elections.
That is irrelevant, if she yokes Britain to the EU in the meantime - which she has every intention of doing. She was and remains a remainer.
Yes, she pulled a Merkel.
The 2022 General Election is on 5 May 2022. The Tories will want to have the new PM in place for at least two years before the election to allow them to build a positive record in office and work out a proper manifesto.
This means that Theresa May will be a backbencher by Spring of next year. Probably resigning after the UK leaves the EU in March.
She won’t leave Parliament until 2022 due to the Tories having the bare minimum number of seats (with the DUP) to form a government.