Gender and Age of my budgies (pictured)?

Hello everyone.

I just received two budgies as an anonymous gift so I have no way of tracing their source and no way of knowing their age, gender, or genetic information. I've read a bit about budgies and caring for them. From what I've read, I believe my blue budgie is a male due to the blue cere and the yellow/green budgie is a female due to the tan cere. Also the blue budgie has a darker purple patch on its cheek while the yellow budgie has a light purple color patch on its cheek. Regarding their age, I also noticed that they still have bars on the tops of their heads but the bars seem to be fading. Furthermore, they seem to have iris rings around their eyes but the rings are not bright white. Both birds are about 15 cm tall from head to tail. From these observations, I estimate their age to be between 4 and 6 months. Can you please confirm my estimate or give me a better estimate regarding the sex and age of my budgies based on your experience? I've attached some pictures of my birds.

https://www.dropbox.com/s/x9936yq9massxa3/Photo%20...

https://www.dropbox.com/s/7g6kfrq16krmogl/Photo%20...

https://www.dropbox.com/s/9zegdra9wgnbmja/Photo%20...

Any help is appreciated. Thank you.