Current price field and Start price in Negotiations

Summary:

We want to Implement the best practice negotiation management process that involves establishing a negotiation process that follows the most recommended and effective methods for managing negotiations. 

Content (required):

I have two questions regarding the implementation of a recommended negotiation process. 

Firstly, is it possible to have a setting where the current price field is automatically populated with the last price entered, instead of having to manually input it? 

Secondly, in relation to the start price set by the buyer, can we set a percentage deviation from the starting price so that suppliers are required to respond with a price that is at least a certain percentage lower than the initial price?