Cotton impressed for the Trawlerboys during a stint on loan towards the end of last season and manager, Dale Brooks, has moved to bring him back on a short-term loan.
Humphreys is an 18-year-old right-back and arrives at the Amber Dew Events Stadium on work experience. The youngster will act as a direct replacement for the departing Callum White after he accepted a job in Mayfair.
After completing the signings of the duo from Southend, manager Dale Brooks said: "I'm delighted to bring Nico back to the club. It's obviously going to help on numbers and will help that he's been here before.
"Daniel is a right-back with great energy and is a tough character. He's thought very highly of at Southend. This is going to be Daniel's first taste of this level so it's important that we're patient with Daniel because it's new to him.
"Having lost Callum, we needed to bring someone in who could do similar to what Callum can do. Daniel has good energy and can get up and down the right-hand side. This is a really good opportunity for Daniel and I'm sure he'll enjoy trying to overcome the challenges that he'll face."
Updated 18:33 - 20 Nov 2017 by Sean Galea-Pace