Are Upsells/Downsells all set up from within the first product's admin, OR do I only set up the first upsell/downsell from there, and set up the second upsell/downsell from the admin of the 1st upsell/downsell product?The former: this is a feature that will be coming soon. It will make set-up a bit easier when you just want to have upsell 1, 2, 3, 4, 5 in a row with no need to change the path based on what someone picks.
The latter: yes, this is how it is currently set up and gives you the most flexibility.
Keywords: Upsell, downsell