Re: the use of ships guns in sieges. See the relief of the Siege of Ladysmith where the Royal Navy transported ships guns over difficult terrain commemorated in the field gun competition
In in world terms I think its easy to write him out - he lost the election off screen and has retired to his estate. The real world side though...that'll be tough.
As a Brit I don't understand the role the FBI would play here. I was under the impression that the FBI only got involved when a state line had been crossed or if the crime was on federal property. Why would they come in and take over what seems to be a local murder case? Just because the victims were foreign?
With regards to Strange's backsliding are we discounting the influence of the Darkhold on him. I get the impression that he had absorbed it, or its power so it must be having a greater effect than it would have had on the main MCU Strange or Wanda.
Was the first guy that Cate broke out infected with the virus? He looked unwell. Had they managed to make it airborne and has Cate's breakout doomed the Supes?
Alternatively will Butcher find the research in the Woods and try to make use of it?
The only other thread I can think of would be the fact that Marie knows the senator has blood powers now and that may have repercussions as she seemed to be keeping it quiet.
It has been an age since I read the books and I may be misremembering but I thought Min wasn't all that interested in Rand but had a vision of them together (possibly with the other interests too) and sort just gave in to the vision as they always come true.