Can multiple conditional bonus attacks activate on the same turn if those multiple conditions are all met?

Question

If conditional bonus attacks can stack with each other, can they also stack as different instances of the same source ability? Like If I kill with Great Weapon Master and then use the bonus attack to kill another enemy already weakened by my group, do I get another bonus attack I can use against another enemy?

With the above in mind, will the build below work as intended, or will it not because of a misinterpretation of the rules.?

I've made a Hill Dwarf Barbarian and I've planned his build up a few levels. By level 5 he will have the ability to combo together a Greataxe + Rage + Reckless attack + Totem Eagle + Great Weapon Master + Two standard attacks per turn.

At level 5 during rage, this gives him a free Dash action, two standard attacks with a +0 attack bonus with advantage that each deal 1d12 + 14 damage, and if any of my attacks kill or critical hit I gain a bonus attack subject to the same prior bonuses. Enemies get advantage on attacks against me and standard "vantage" (instead of disadvantage) on attacks of opportunity against me.

If the campaign lasts this long, I would further plan to take the toughness feat at level 8 in order to decrease the damage as % health per turn against me / damage as % healt

I also will take Attuned Wolf at level 14 to make enemies I attack prone on hit to reduce enemies that could strike me with advantaged attacks.

Answer 1

No, you can only take one bonus action per turn. From the Player's Basic Rules, page 69:

You can take only one bonus action on your turn, so you must choose which bonus action to use when you have more than one available.

So for example, with your above build, on the turn you use Rage, you can't use any of your other bonus actions.