How do Malphites Brutal Strikes interact with Crit and Lifesteal right now?

Hello,

i am still not sure weather or not i get this right:

Malphites brutal Strikes buff his armour passively and adding bonus damage to his basic attacks if activatet right?

Now can the bonus damage on the target given by brutal strikes crit? If so, does it crit whenever the attack itself crits or is it possible for the basic attack to crit and the bonus damage not to crit?

Does the bonus damage apply lifesteal or do you need deaths dance to profit from the damage?

Same goes fpr the AOE damage, can it crit, if so does it crit for itself, together with the single target bonus damage or together with the single target bonus damage and the basic attack? Of course the AOE damage will not apply lifesteal, only the heal from deaths dance reduced for aoe right?

Because if both forms of bonus damage from brutal strikes can crit and do always crit all together with the bonus attack, it would be possible, in theory, to built a full armour malphite with one infinity edge and all runes on bonus crit damage and just jump in an enemy team with the ult, hit someone and hope for a crit right? Cause in that case he would deal a MASSIVE amount of aoe damge and obviously an even greter amount of single target damge, while beeing only killable by the still standing AP-chars right?

Greetings