I live in Illinois just south of Chicago and these plants were transplanted last fall.
Cut those off immediately so the rhubarb can put its energy toward the stalks. Here's a helpful article:
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/rhubarb-bolting.htm
Can rhubarb be divided
Yes, it certainly can be divided. Here's an article with tips:
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/dividing-rhubarb-plants.htm
I have always thought you shouldn't but have been told there is no good reason for this
Here's what our experts have to say:
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/can-compost-rhubarb-leaves.htm
Hi! I was cleaning up my rhubarb plants and I saw seeds I’ve never seen. I picked them, eager to plant!! As I’m researching I see I was supposed to let them brown first. :( Did I ruin them? Thanks, Jenn
They need to be brown to be ripe seeds.
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/harvesting-rhubarb-plant-seeds.htm
What is causing it and how to fix
This article should help:
https://www.gardeningknowhow.com/plant-problems/pests/insects/holes-in-plant-leaves.htm
during the summer season, once pulled and cut, is it best to replace the stalks over where it will continue to grow?
These articles should help:
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/harvesting-rhubarb.htm
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/grow-rhubarb.htm
Sometimes these lesions ooze what seems to be lie sap I have no photos available
Unfortunately, there are too many to list. These articles will help:
https://www.gardeningknowhow.com/plant-problems/pests/pesticides