If I continue to work beyond age 70 (and continue to contribute to SS), will my monthly benefit be adjusted to take account of these additional contributions?
Maybe. Social Security retirement benefits are based on a person's best 35 years of inflation adjusted earnings (https://www.ssa.gov/pubs/EN-05-10070.pdf). As long as you continue to work and pay into Social Security, your monthly benefit rate can go up, but only if you earn a higher amount in a year(s) than one of your previous best 35 earnings years.
Social Security automatically recalculates benefits for current beneficiaries on an annual basis if they have additional earnings that would increase their benefit rate, but you can submit proof of your recent earnings (i.e. W-2s for wages, Schedules SE for self-employment) and request a manual recomputation.