Building a Interactive Pet site

We're in very early planning for this website, we're still seeking an artist to help us create concept art and all the sprites and artwork we want to use. But if your services can provide that as well, please let us know. At this time, because we're in very early planning, we to avoid providing certain information, until later down the road when there's a confidential agreement signed. But it is accurately, an Interactive Pet site. The best example to use would be something like NeoPets. But we want a lot more features to it. We want user interactions, set game quests (defeat certain monsters, retrieve certain items & whatnot for rewards). Want a cash shop system for donations to access special rewards. We want player leveling to unlock level restricted area access, item access, quest access, etc. We want players to have job skills, limited 1 per character. Job skills open up to item crafting, specialized item farming, etc. We want a mobile platform, so that iPhone & Android users can play from their phones and tablets. We want a fighting system that allows these the pets to battle. We have our own established forum community, and we want this to be built around the existing software. The admin tools should be built directly into the Admin Control Panel. We are seeking reputable developers (meaning more than 1) to work on this project, we've had a few that tried to tackle this on their own and have come up extremely short. We will bring in our own professional Developer to oversee and manage, to ensure everything is moving forward. Just a reminder, we're very early in the planning. And may even want to launch everything in 2015 some time. We'd like to see what our cost options are, and how much time it would take to complete.