Hamster babies general FAQ's

[loren fontan]

Hi everyone! i'm new here.
My hamster has 7 pups who are currently 6 days old
I have some general questions that I would love some help with.
Once i have figured out the website im thinking i will make a thread about my babies.
1) what is deemed as a healthy weight/size for pups?
2) the runt (squish) has a little red mark on the top of its head, almost like a bruise. do i need to get it checked?
3) what age can i sex from
4) can anyone tell me what the development stages are for the babies. Ive done my research but want to make sure im doing everything i can so they will be happy and healthy.
Thankyou in advance!!