Negotiations with Sales Team … Are these valid concerns?

Run away.

Who paid for the app? Who requested the app to be built?

If the sales people paid you to build the app, it's theirs. If not, you are paying them to sell your stuff which means you should not have built it if you don't have a customer or one in mind that you yourself will approach. You wasted a lot of time building something when a customer or sales person didn't request it.

True sales people aren't going to ask for complete ownership unless they are willing to pay for true ownership. This means, they cut you a check or you two start a company together. The sales person can't sell something they don't own or have the right to sell on your behalf. So if you aren't in a company together or they aren't willing to pay you upfront for the software, you are wasting their time. If they can't afford the software, you need to place the software in an entity you both own.

Offer them a performance based contract. They get exclusive license to the code for X period. During this time they need to either a) close a funding round of Y or b) pay you Z to keep the exclusive license or else the license becomes non exclusive and you get to do license the code to anyone else.