Dear friends,

Construction and development involve various or numerous parties namely the clients, project managers, consultants, contractors etc.

Which one should take precedence - various or numerous ?
Just choose one. The two of them create a redundancy.
either, depending on the emphasis you wish to put over.

The number of other parties - use numerous

The variety of other parties - use various.
Teachers: We supply a list of EFL job vacancies
In this sentence, better use numerous or various ?
 nona the brit's reply was promoted to an answer.
Students: Are you brave enough to let our tutors analyse your pronunciation?
I would prefer using various because your talking about a variety of things. It would sound better for the sentence.