1. You are referring to the practice of ESN cloning. If you go that route, then lists are obsolete. ANY CDMA phone available could potentially be cloned to Boost. All of them. No need for lists, just look up CDMA phones and select the one you like the best. Then contact a cloning service, if you wish. As for the legality, it is considered illegal, but no person has ever been charged or convicted with illegally cloning a phone they intended to use on their legally existing account. Considering that cloning CDMA phones has been around for almost 2 decades, that is quite the testament to the notion that cloning of CDMA phones has been made illegal to deal with phone thieves, terrorists, spies, people who want to steal someone elses minutes by cloning a legally owned phone, etc.
2. Obviously, when you clone a Sprint phone you will not need another ESN to switch from iDen to CDMA. That phone, after cloning, will have a usable ESN for you to give to Boost.
3. A Sprint phone with a bad ESN can not be used on either Sprint or Boost. The only thing you can do with a Bad ESN phone is clone it. You have to send it to a Boost cloning service (find on Ebay or Craigslist, prices range from $80 to $140 for the procedure.)
Quite honestly, I would recommend not going that route in your particular case. I would get one of the existing Boost Android phones and switch from your iDen phone to Boost CDMA in mere minutes. Phones range from $99 to $299, and everything inbetween. Plenty of very good phones to choose from.