29 gallon tall is 18" tall, as opposed to 12" like he has now. I don't think the extra height would really be a big deal, but checking anyway.

a lid is a must. The crazy frog almost killed himself getting out, although I think that was due to ammonia level too high. Since then I make sure the water is in good condition and have also sealed any possible exits.

With the fish, if he eats a couple, so be it. I just don't want him getting hurt. ideally I'd like to have a nice tank with a couple more real plants and some fish that He leaves alone. I was considering getting him a female friend, but the eating of the tadpoles would be grim. as he's never had a tank mate, I'm not sure how he'd get along with another male.

cheers