Unfortunately, we did not look for such plugins, so don’t have suggestions for you, sorry.
a) you can do this if it’s suitable for you
b) Go to Appearance > Widgets > remove widget from the Discount page widget area
c) What do you mean by fix “View all products” page? Do you want to load more products by click? Then enable load more button in the Products element settings https://prnt.sc/zr1x7c
At this moment “View all products” is a simple link https://prnt.sc/zr22qs that you can change if you want to redirect users to another page.
