It's hard to say for sure in fanfiction as different writers can create different scenarios. But generally, Superman has the advantage. His power levels are often depicted as being extremely high, like being able to move planets. Homelander is powerful in his own right, but he seems to be more limited compared to Superman. Superman's powers are also more iconic and well - defined, which might lead more fanfiction writers to have him come out on top in a battle against Homelander.
Definitely. The comic version of Homelander is portrayed as having greater strength and capabilities. This is evident in his confrontations and the scale of his power displays throughout the comic series.