Don’t about big companies but how our company works is
Q. How they start to develop website or application ?
A. We usually follow sprints (Agile/Scrum) which lasts for 2 weeks max, and the work is divided to developers accordingly (frontend, backend and devops)
Q. How they manage their software project’s codebase ?
A. Using Git (version-control system) and Github or Bitbucket to save the code in private repositories
Q. How they divide the work between their employees ?
A. Work is divided between software engineers will be based on requirement mainly frontend (UI & UX), backend (Ex: java, python, c etc) and devops (Infra, VM setup etc)
Q. How they complete projects in proper time ?
A. Planning, as mentioned earlier we will plan our work before a sprint meeting starts and will review all the changes at the end of the sprint (usually a sprint last for 2 weeks)
Q. How they deploy website or application successfully ?
A. Depends, your own server or on premise or cloud, you can also use tools like jenkins and github actions for automated code deploy (CD)
Q. Do they deploy website or application with proper documentation ?
A. Yes, now a days everything will be stored in version-control system (Git)