I'm not sure where you can get more Tigerfish from, i'm in the UK and I waited two years for mine.. There seems to be quite a few people with baby ATFs this year though, maybe they're becoming more available..
Mine are in a 6ft, 150gal tank for now, it has two external filters and one external heater. I didn't have any trouble getting them off live food, they weren't too keen for the first day or two, but now they're ravenous feeders..
As for live food being good or bad.. I don't have a problem with it, it certainly makes your fish grow well.. most of the fish i've kept for the last ten years have been fed on mainly live food and i've never had any health scares. Maybe i've just been really lucky, but lots of people panic about it.. Now I have the ATFs, i'm really enjoying the money i'm saving by not having to buy hundreds of fish every month, feeders aren't that cheap in the UK. It's good to get them as a treat now, instead of having to buy live..