This is the part where I need to find Snake from the Seedy Bar. To investigate Cicero's whereabouts. Snake is needed too when Crossing the Silent Plains up to Ra'kash Ruins so you can find Graul Scale by fighting the black skulled Graul (Imps as they were called themselves)
Yes, it is. It will make the battle to Warlord (Arihama) a bit easier and you will amass EXPERIENCE for your mc. Equipments will add to your mc stats, so you can kill the boss efficiently, Pills that can be hoarded from the through Galactic Union (GU) Missions. It will shorten the amount of times battling the Warlord, mitigating impacts of anyone dying from the same battle.
SPOILER some of the crew members will die. e.g. Hakkon (The Subguhnir Alpha, if you choose to hire him in Akra), Bradley (if you didn't gotten to the side quest) NPC: such as Riordan (can die too if you choose let him join in the battle).
NOTE: They will not, if you didn't make the battle for a longer amount of time. Or you choose to exclude them, like Rylan (due to his brother's wishes) or Hakkon.
Bradley's chance to die is from prolonging from the battle or not doing the side quest too.
(If you killed the Subguhnir Alpha at Akra, you cannot have him (Hakkon))
Trigger the side quest would be if you already talked Bradley after he came back a day after meeting the Sithyryan Council. (Wait a day). Then there is a "killing the warlord" conversation. Wherein Bradley will talk about his punishment and he will proceed to relay the side quest to you in the same conversation.
Partly, but you can also go to the boss fight too (if you want to sacrifice Bradley which is most likely due to not finishing the meta-sith side quest.) It will cement the impact on your crew members in later. But in lore aspect, all of your crew hate Bradley too.
There is a high chance that Rylan and other not powerful characters would die. But Feraldo and Skru'Vaks would not (cause they will flee in the battle if your crew dies in the event.)
They weren't required but yeah, side quest is needed in order to build mc's stats and team stats. Don't be afraid no month, day or time cycle mechanic that kills the character... But the duration of the boss battle will likely kill some of them as I stated above (my own game experience). It is highly recommended, that you kill Arihama (the Warlord) in short shots so no dying character will deducted from the roost of crew members.
Though R.I.P to my Hakkon... his sacrifice will never be in vain.😭😭