Normally keyword stuffing refers to repeating a few keywords many times. However, lists of many diverse words may also be a problem in some situations. I have one client who lists 42 suppliers on their site and they haven't run into trouble with Google rankings. At the same time, those suppliers are not in the content area, they are in a sidebar.

It seems to me that 100 brands on the home page might be a bit much - is that really useful for your visitors? If so, how much of the total page content is taken up by the brand names? Is it more than 50% of the total word count?

Might be near 50% of the word count. Probably not so useful to the reader although some are links to more info on that brand. I must admit, I included them for Google more than my readers. But I'm sure my readers are searching for those brand names. Guess I need to find a more natural way of including them in content.

Yea probably. Because you will competing not only with the brands themselves for Google traffic, but also with everyone who sells those same brands.

No

No to what?