Since Jam making uses natural acids. Metal+Acid ------>salt and hydrogen. Since aluminum is high in the reactivity series it will react with the acid from the fruit quickly forming metal based salts in you jam. A steel pan which is lower in the reactivity series will not produce salt quickly so your jam wont be ruined.
You shouldn't use a pan, you should use a pot. A large pot preferably. Depending on what you're stewing, of course.
Animals should not be encouraged to eat rhubarb
Stewing - or cooking - should reduce the number of the vegetative cells of spoilage organisms. Some will likely survive.
Any animal should not be encouraged to eat rhubarb
Rhubarb is good if you have gout but don't use too much sugar.
Rhubarb leaves should not be fed to animals
Animals should not eat rhubarb, they will certainly need the attention of a vet. as soon as possible
Yes. Rhubarb leaves are poisonous, so it is highly recommended to take your god to the vets if you suspect it has eaten a rhubarb leaf.
Aluminum
The leaves are poisonous and should not be eaten
Not closely. Celery belongs to the parsnip family, and rhubarb belongs to the buckwheat family. Celery is an annual, while rhubarb is not. They do visually seem like they should be more closely related though.
It is not recommended. Here is a link. http://www.livestrong.com/article/519736-is-rhubarb-root-safe-while-breastfeeding/