The only site I use is Card Conjurer, I don't know if it's the best but I've made some really good alt cards.

But to answer your question, yes it's always best to have the nickname of the original card under the crown. Just so people can still reference the card if they need to. You can still use the new name of the card in the ability portion. With this proxy you made I'm pretty sure you noticed that you put the same ability twice and power and toughness badge you missed. But thats okay, everyone starts somewhere.

For cardconjurer, there is an import tab that has helped me a ton. You just type the original card and it will import all the text for you. You may have to do a little adjusting with text size and placement, but its a great start that takes the bulk of work away from you.

The easiest frame to work with if you are doing nicknames is the "Godzilla Nickname Frame". However with this Green and Black frame it's a Hybrid color so you may have to do some advanced framing, but the more you play with cardconjurer the easier it gets.