Return to the Reik Books and Challenges

The first Tome is close to the start of the mission. After you get to area with the waterfall, stick to the left and you'll find a Troll cave where you have to fight a Bile Troll to get out. The tome is in the middle of the pit.
There's currently another way to get the tome without fighting the Troll that might get fixed. If you ignore the troll cave or take the burning ship shortcut you'll be at the River Warden Camp Site area.
Stick to the slopes to the left and you'll get to this rock you can jump on to get to the Troll Cave exit.
You can walk through the spike barriers and get the tome in the pit.
If you get too close to the cave's entrance it will trigger the Troll spawn.

The 2nd tome is just before you exit the cave connected to the first Rotblood camp. Turn to the right after passing this torch/hole. It's in the chest.

If you're playing as Battle Wizard, Slayer, Handmaiden or Zealot then you can jump/dash from the start of the cave so you don't need to backtrack later. You have to jump before dashing if you're using HM/Zealot to get enough distance to reach it.

After the first Rotblood Camp keep going forward past the ruined house until you reach the beach.

To your right will be a small tunnel barred by chains and inside it will be a key.

Now you can open the trapdoor in the ruined house which leads to an altar with the grim.

The third tome is under the bed on the top floor of the ruined house.

The 2nd grim is on the Skaven ship that you have to blow up with barrels. On the helm of the ship, go up the ramp on the right side and jump on the wooden boards to get to the roof where the grim is.

Or you can reach it from the barrel spot/steering wheel (the dwarf might not?)

There's a little shortcut at the start that skips straight to the barrel/cave entrance section if you don't need to take the 1st tome or want fight the troll. Just jump from the burning ship, to some rocks to another crashed ship and walk along the mast back to land.
You can also skip most of the cave if you're using Battle Wizard, Slayer, Handmaiden or Zealot. Just do the same trick mentioned in getting Tome 2 but aim to the right on the higher ledge.

Give 'Em A Volley challenge
After you start the ship, run to the port side(left side if facing forward) and stand directly behind the right cannon. Just before this tree lines up with the cannon, start firing it.
Then switch to the left cannon and start firing that too, then run back to the first cannon and fire it once it's ready and then the left cannon again. depending on the timing, both targets should be hit by just the right cannon but just in case it misses, then the left cannon should hit them.

Scuttling Scoundrels
Wait for the ship to circle around to your starboard(right side), once it's about to line up with your ship, start firing the right cannon then the left one. If you time it right then you'll hit the 1st ship just as its health bar shows up. Then wait for a few seconds for the 2nd ship and fire the right then left cannon again. After that, the first ship should have just about crossed over so run to the port side and fire the right then left again and wait a few seconds for the 2nd ship before firing both guns again. Both ships should be down at this point but if you missed the timing on the first ship then it should be the only ship left at quarter or half health. You would have just enough time for it to circle back and line up with the other side's cannons.

Overwhelming Firepower
There's a chance that a Chaos Warrior will spawn standing directly in line with one of the cannons just before you start the ship, just make sure not to aggro him. If not then try getting another player to lure one. If you're playing solo, then your best bet is to run to the ship after lighting the beacon at the beach and spamming the cannons while the horde is running across the beach.
Casting Off
Requires coordination with a full team since bots don't hit the grapples but one tip to make things faster is that Grail Knight's Blessed Blade and Shade's Infiltrate deals high damage to the grapples, and hitting the grapples doesn't break Shade's invisibility.
You have to destroy the 3 sets of grapples from the first ship fight quickly because you need the rest of the 60 seconds for the Skaven ship finale since the timer starts as soon as you get pulled in by the 2 grapples.
Fire the cannons right as they start boarding your ship to kill any rats waiting on their deck then split up to break the warpstones, two players to climb the opposite ends of the ship and the other two to work on the larger machine in the middle, splitting up to break the shards on both the top and bottom part of the orb then running back to the ship to get ready to break the grapples on each end.