Both of these are very loaded questions that are hard to answer in short form. For any software product or app you really need to go through a specification process before any development shop or developer is going to quote you (at least the good ones). One of my various gigs is specifically doing this and I've help all kinds of founders get through the spec processes. That alone will cost you between $1,000 and $5,000 in my experience depending on the scope needed and the skills of your spec developer. However, the cost of the dev project will drop at least that much in my experience because of the communication and expectations going more smoothly, so I think it's worth it.

With respect to fundraising from investors you are going to have to go through a full business model development process which may or may not include revenue planning. You definitely need someone to help you through this because it's not a short answer.