Age varies on too much to tell unless you know a hatch date. If its under 115 grams its probablly only a few months old at best beyond that its a guessing game. As far as enclosure you can do as big of a setup you want as long as you can keep an ambient temp of 89 in the enclosure. Now feeding live vs ft. Live feeding will always keep the kill response good which equates to good feeding response. Also you dont have to worry bout things like salmonella or other things that can come from feeding frozen. Also they process and digest live better. If your worried bout the prey item biting then simply grab it by the tail and give it a good whack on the head against something hard to stun or knock it out first. Ive fed live for 20 years and as long as your paying attention you wont have issues. If anyone remembers recentlly mice direct had a huge salmonella outbreak with their frozen rodents and it sparked a 50 state recall. No wY id ever take that chance