Here is a past discussion that should be helpful. I am all for getting any animal you are not planning to breed fixed. Why would you take the chance on him making accidental puppies? There are already enough homeless pets in the world.
Here are some other older discussions I also found that might answer some of your questions :)
I am sure there are many more, these are just the first couple I came across
Hi Brittany, Chancey & Cooper, how old are they? were they tied and actually had a successful session? What are the "bad behaviours" you described and what exactly are your concerns?
I say neuter just because, well, why not? My aunt just lost her un-neutered male lab due to testicular cancer that spread to his liver. Despite what people say an un-neutered male is more likely to be dog aggressive, more likely to mark inside and outside, more likely to hump anything and everything in his path, more likely to escape from your yard and roam. While healthwise many studies are showing there aren't as many health risks in un-neutered males, the hormones to affect their behavior and the longer you wait the more likely this is going to become a habit vs something you can easily deat with. None of my male dogs are aggressive, mark, roam, etc and all are happy healthy boys who were neutered around 6 months old.
Just for the record: at 8 wks you are not looking at sexual behavior ( the pup is nowhere near sexual maturity ) but rather at play dominance behavior. You can have both males and female pups do this, regardless of the sexes involved, and dogs will try this with people's leg as well. They are all attempts to assert dominance. My guess is that, by the time this pup is 6 months old, you probably will not be asking about neutering or not.... :-)
In case you are interested in having him fixed, there are also a number of past discussions about the best age to neuter a male corgi
I would have them both spayed/neutered personally.