There appears to be a problem with your question since your essay topic differentiates between 'formal talk' and 'social talk', whereas your question refers to talking to employers/employees and to customers. I would suggest that 'work based' conversations, between employees and employers, are 'formal', as are 'business' conversations between employees and customers. It's only the 'office chit chat' (or casual conversations, not related to business, between employees and customers) which fall into the category of 'social' talk.
'Formal' talk is characterised by one participant taking the lead, or adopting an 'expert' position. So an employer (or a manager employed by him) will give instructions to his staff, or field questions from them. The senior figure will not normally expect to receive instructions and the only questions he'll expect to ask are in relation to checking that his instructions are properly carried out (rather than having to find out how to do something himself).
The relationship between an employee and a customer is also 'formal' but the power base is flexible. For example, a customer might go into a DIY shop seeking 'expert' advice from the guy behind the counter. The store assistant has the upper hand in the power stakes because he is the one who gives instructions and receives questions. However, later in the day the same assistant might be faced with an experienced tradesman (who knows more than he does) who has come to complain about a product which he purchased. The power base is then transferred to the customer, because he will be making the demands.
As an example of 'social' talk, an employer and an employee might both be fans of the same football team. When, on Monday morning, they both discuss their team's performance on Saturday, their is no 'power base' on either side of the conversation. They are speaking from positions of equality. The same would apply if either of them later discusse