Naruto's mother is some random Uzumaki OC...

A month before Naruto's birth Kushina was attacked by Obito and ended up in a coma... to make sure her body doesn't deteriorate or age(since they didn't know how long she would be like that) the Third ordered that they activate a seal created by Mito Uzumaki that halts time around the person in a coma that will deactivate the minute there ready to awaken...

A few days before Naruto's birth... Roshi... the 4 tails host was attacked by Obito and the 4 tails was riped out...

The day of Naruto's birth Obito unleashes the 4 tails on the leaf with Minato Namikaze sealing it in Naruto...

Kushina wakes up half a year before Naruto graduates and is assigned as his teams sensei...

After the 3rds death Kushina becomes 4th Hokage(Minato declined the position when he heard that his wife was pregnant and had been planning to retire after his birth...)

As for Shizune... while she and Tsunade were still traveling around they visited Suna and Shizune stumbled upon Sasori's old workshop...

Ages...

Rookie 9-12 whatever there called...: 13

Naruto:14

Kushina: 20(her bodies 20 but shes actually 34)