With respect to safety, I think you should split it up into on-river safety and off.
I presume you mean the White Nile near Jinga?
Lots of back packers/overlanders pass thru here.
The river itself is pretty good wrt dangers you'd normally expect with big volume water. And there are lots of access points, it's not like the Zambezi or Colorado that are in deep gorges.
Off river is a bit different. Is a malarial area and sure hospitals probably not somewhere you'd want anything really intricate done to you, altho Jinga the nearby town has what seemed to me to be a reasonable clinic. The river water is pretty clean, I don't think many people get sick from it after rafting o kayaking. The risk from robbery or violent crime is pretty low too I think, compared to any other African river. Well, is probably same as the Zambezi.
I'd ask Jamie at kayakthenile.com for his feed back on this as well. He's an honest, straight forward guy.
Best regards,
Alan Jarvis