So many questions, new duckling owner

[Ilovemyanimals86]

Hi there, everyone calls me Red.
So what happens was.... I went into tractor supplies to get fees and other stuff for my other animals. My kids saw ducklings and then I did and boy was I in trouble. These little baby' looking up at me. I just had to give it a go. I got 4 and got everything I needed for 5 day old ducklings. Built them a nice big home as soon as I got back. They are thriving. I just have questions lol lots of them. I was told that duck forum was the place to go.
So here it goes....
Daughter 1 duckling is yellow and names snowflake
Daughter 2 duckling is very little all black named munchkin
Son duckling is yellow no name yet lol
And my duckling is black and yellow and is the biggest. Name Stark.
• daughter1 duckling is getting bald spots around it'
Wings, had a dark yellow spots on its body in thinkng areas. Why is this and what can I do?
• I believe stark is a boy. All three follow him every where... He follows me lol. Why would they follow him and fuss all over him? Is it because he is a boy. I think he is. I tried to look but I was scared to hurt em.
Can anyone help me on this.
Thanks bunche
Red

 

[chickens really]

Noodling and is the Brooder too warm..Possibly losing down to get feathers?...A picture would help..