What are my legal options? Do I have ownership of the unfinished application?

As noted, this is just way too specific for a free and quite public Q&A platform. Any and all written agreements will have to be carefully reviewed...

What type of attorney do we consult

This is an IP / copyright matter. I suggest that you consult with a lawyer in private and discuss your objectives in more detail. You can start...

Before you do anything further, you need to have a proper case/matter analysis conducted. The general concepts cannot be claimed nor protected only...

How do you terminate a Joint Venture that doesn't exist?

You have to have the agreement reviewed and with an eye towards the jurisdiction where it would be enforced. So if it is governed by British law...

Do I need a lawyer in order to "trade mark" an idea if I'm combining two products that have already been marketed to the public?

You received some great responses. In short, the trademark speaks to the brand identity or product name (e.g., McDonalds, Big Mac, "I'm Lovin It"...

The biggest problem you face in the first instance is to resist the urge to be your own lawyer. Before you start sending counter-notices and...

Would the app as I've described it be considered "commercial use" and require a permit under one, both or none of the scenarios?

You received some good responses. You need a proper legal opinion and even before anyone addresses this rather specific legal question, there are a...

Thanks

No, this was not any kind of due process nor does it mean you were charged with anything. This is just a notice that states that you voluntarily...

Is it unadvisable to apply for more than one trademark at a time if they contain similarities?

While your question is appreciated, it just cannot be addressed in a vacuum. There are times when what you describe might be overkill and then...

How can I legally sell a popular name brand on my buttons?

I will discuss the trademark process as it relates to your own brand in more detail below. Now regards to selling items with other famous brands...