I'm afraid the tank you have is totally unsuitable for goldfish (or any fish to be honest). See the article linked below for more information. I'm sure one of the moderators will be along shortly to advise further...
Don't know much about killifish so can't vouch for the quality of this. Has an interesting chapeter too on culturing your own live food and homemade fish food recipe which a few people were discussing recently.
The biorb also has a sponge ring in the bottom which although not the main biological filter I would have thought will still contain a fair amount of bacteria as a starter to seed the new filter? If so you could chop some of this up and bung in the new filter to get things going.
I'd be up for some sort of Scottish meet up. It might be a bit awkward if it's just the two of us dismalscientist, especially as I am a renowned womaniser, fishkeepings answer to Peter Stringfellow or John Prescott, but we could see if there's anyone else north of the border interested?
I just found this online, it's a free to download Australian aquarium magazine. There are 7 back issues available in pdf. I've only downloaded the latest issue so far but it looks decent enough..... http://redfishmagazine.com.au/editions