sigurd eye(rogue)

[Gork]

I can't get this eye i tried to steal it, didn't make it and no second time allowed, challenged him he chicken out.
know its seems i have to do quest to help people.
I don't know how to get the cat, the flowers, clean the tomb( the tomb not sure What i did wrong) and kill regni brother)

[MassConnect]

Just use a fish on the cat if you have no animal ken or climbing

The flowers will depend on what you've done so far in Nidavellir:
Eitri wanted to trade something for a human tool (ice pick, shovel)
Eitri wanted the footprint of a cat (use ink on the cat while you have the librarian's note in your inventory)
Eitri wanted news from Alviss (use the Eitur {reward for putting the Haugbui to rest} on the strange stones on the screen where you would find the Mugwort that Aurvandel wanted)
One of those three you probably already did and got something. Do the other two to get the flowers and a runic stick you'll need for the tomb.

Not sure who told you to "clean" the tomb. You need to ask Sigrun for the key after rescuing Heime, then unlock the door, go inside, open the coffin, use the runic stick from Eitri on the corpse, talk to Helgi, take his skull, then go back to Sigrun with it in your inventory.

You have two options for dealing with Fafnir (Regin's brother) as a Rogue:
Go to the cave in Svartalfheim that has all the bright crystals (it's at the end of the path on the other side of the cavern you have to jump or climb across)
Use your lodestone until you find that something (a chest) is hidden. Pick up the invisible spot to get Regin's chest and Fafnir shows up, initiating combat.

1) you can just fight and kill Fafnir in combat
2) you can run from the fight, keep running back to the screen overlooking the lake, and you can use the chest on the cliff to throw it away. Fafnir jumps off the cliff in pursuit of the chest, but will die from doing so.

[Gork]

climbing with the cat doesn't work, and catching fish i need ken animal or luck to aesir( how do i get luck)
i caught the cat, had to be stealthy at night.

[Radiant]

There's other places to get fish, for a rogue at least...