so for instance i have 100 sf of wall to paint. when i want to calculate durations using the sf data and the productivity / worker / hour data, how can i translate this 100 sf of wall to work?

for example if i know that one worker can complete 100 sf of wall in 8 hours, then does the work become 8 hours?

in other words,

1-does the work mean the amount of time required for one (1) unit to finish that entire task?

2-in general, when i have sf data, and productivity data, and when i want to translate this into ms project to come up with my duration, is the work column where I start? if not which column i start with? if work column is the place to start, then i enter resources available, assign resources and then it calculates the duration? is that the sequence?