From what I am seeing here, it looks like you are searching for a great deal. Good for you! As a buyer you want to get the best possible deal you can. But at the same time, you want a house that fits your needs and will turn a profit when you go to sell it. If one of my clients asked me the questions you are asking, I would do one of three things:
1) Call the listing agent and ask them, "How flexible is your client with the list price?" in some cases, the listing agent may disclose information authorized by the seller. If the house has been on the market a long time, you will have more options. But that same conversation may reviel that if they go lower, they may be a short sale. Or you may discover they are just weeks away from a Foreclosure. A lot can be learned from this quick call.
2) instead of writing a full offer, you can put together a letter of intent. That is just a one page summary of what you would bring to the table and offer. Now the other agent will not like this, because as stated below, most Listing agents want to see your full offer with all the right papers. But in some cases, like yours, it might make sense to see if they will go along with your ideas for buying the house. If so, then a full offer can be written and the real negotiations can start.
3) If you really love the house and just have to have it, write the FULL offer. The "best deal" on a house is not always the cheapest price. If you really want a house, your agent will need to do what it takes to WIN the house for you. They have to read the other side to find out where can we push, and where do we need to give. That is our job = to get you the best "deal" for you and that house.
Feel free to contact me if you have any other questions along this line.