On the first time I trekked up there, we were descending toward the Dudh Kosi River. We were pretty hot, and we wanted to splash some river water over our faces before we continued. The Sherpa guide told is not to, because it was a sacred river and bad luck would befall us if we dipped our hands into it. We did not want to disrespect the Sherpa, so we continued on our way.
Later on, I figured out what the truth was. That river is downstream from many villages that have no waste treatment at all, and "everything" ends up in the river. It was not bad kharma to dip into the river. It was simply a viral field. Without knowing what water treatment you intend to use, it is hard to say.
You want a sleeping bag good for near freezing temperature (inside the tea house), worst case, and some DDT powder for the lice or bed bugs.
The rhododendren forest ought to be nice at that season.
On one trek, all of the water that we drank had supposedly been boiled by the Sherpa cook staff. But then the majority of the trekkers got sick with Giardia by the end of the trek. The Sherpas might boil the water, but then pour it into an unclean vessel.