The controller of each Warrior token created by Najeela chooses which player or planeswalker it's attacking. The tokens don't have to be attacking the same player or planeswalker as the creature that caused the ability to trigger. They can even be attacking players or planeswalkers that weren't being attacked.

Untapping an attacking creature doesn't remove it from combat.

Although the tokens created by Najeela's first ability are attacking, they were never declared as attacking creatures (for the purposes of abilities that trigger whenever a creature attacks, for example).

There is no main phase before the additional combat phase. This means that, for example, you can't activate an equip ability between combats.