Sounds like seeing all at once is the preferred way. For each item offered, there will be included a column telling you who is offering it, and where they are located.
I may even make it so you can have the list show only those from a certain member, or all at once, and make it your choice which you see. You could switch between seeing them all or just seeing the ones from Horntoad, for example.
As for the ordering, that may be very difficult to change. I totally understand the desire to have options to sort by different ways (common, latin, etc.) Right now we have a plant name field and I'm sorting on that. But that's common name sorting since the common name comes first in the name. I'll just have to give some thought to that one.