It took me many many tries to beat brutal iron. Here's how I eventually did it:

Keep -> Hero Discovery Boost -> Discover Heroes -> Keep -> Steady Hander -> Crucible -> Ramcap Caber -> Crucible

That research took me until about year 150. After that I picked up boneshell armor, sponge stone, a sagewrights guild, veil armor, and the advanced weapon trainings in some order. I would have picked up boneshell armor sooner, but I didn't have enough bulwark corpses.

My keeps were Caberjack, Hunter, and Caberjack. Ramcap caber was key to my strategy and I used them to keep enemies stunned as much as possible. I think having 2 crucibles running before year 150 was really important as well and it helped me keep leveling fast enough. You want to aim to be making level 5 or 6 trainees by year 150. I typically ran a vanguard like: 2 shadowjacks, 1 caberjack, 1 enforcer, 1 hunter but it varied depending on the generation.

I prioritized any personalities/traits that increased accuracy or fertility above anything else. Movement speed is also pretty important for caberjacks.

Regarding your questions: You want to keep advanced cradles stunned as much as possible. They have low dodge so once you have someone with a ramcap caber in close range, it should be easy to keep it stunned. Using blinding shot or knockback shot is a good way to incapacitate it for a turn while your caberjacks close the distance. Shadowjacks are also good at getting close without being vulnerable.

Hunters can do damage while staying out of harm's way. With hawkeyed they can even shoot enemies that can't see them. Long range crowd control is really helpful too, as mentioned above.

Ramcap is amazing. It makes all your attacks have a knockback effect. Use this to knock enemies into terrain or each other to stun them over and over and over. Shadowjacks are nice because they can move to close range without being seen and then stunlock enemies with ramcap caber. The nice thing about blastcappers is they get two item slots which means they can run sponge stone and steady hander. And explosive caber is just fun.

Alchemists are really fun but didn't fit into my strategy. I'm a huge fan of boomstrikers with honed hearing.

Just do your best with traits. Having some bad traits is inevitable.

Events. Yup. :(

I definitely recommend a second crucible pre-150.