In character I know Adam would not like options five, six or seven. He already thinks that Second Chance has information that could be of value and that the city needs help. Option one seems reckless also, considering there are injured members of the team. Option three is somewhat better, but the risk of friendly fire and the fact that not everyone would be able to swim well make it impractical. 

Options two and four seem the most practical, given the story so far. In option two, Adam could create cover and camouflage with his magic. In option four, Adam could do that and be a distraction through shapeshifting (less bear attack and more along the lines of scaring the enemy away), since James would get his healing magic back.

My vote is for option four, with Sil flying letters to and from Lucy (or some other trusted person in Valheim) to plan and coordinate a successful infiltration. Option two would be my second favorite. In any scenario, I would also ask the wagon driver to have someone ride to the capital to deliver news of the seige, paying him if needed for speedy delivery of the news.

Of course discussion of this is cool also, those are just my thoughts.

By the way, if anyone wants to use my most recent post as a springboard for theirs, feel free! I set it up so people would have flexibility in that regard.