Socket.IO Full-stack work in progress Website

The Website has been developed couple of months ago and still a work in progress , I need a skilled full stack developer to keep working on it based on the Milestones we have. We do work per milestone, as we add new features every week we need a fast good HIGHLY skilled developer to work with us , with the following conditions : 1. No Down payment will happen, We post the milestone with funds before you start the work, once the milestone done we release the funds immediately 2. We are looking for a long term relationship with the developer we will hire, to keep the project going even after the initial state . 3. The First Milestone will be a (testing) milestone, and if the developer "struggled" we will terminate the project immediately and start over with a new developer, with Zero payment to the developer . 4. The Milestones will usually be separated with tasks, each Task has a deadline, specifically for the first Milestone, not to be able to fulfill the deadline, we will terminate the project Immediately, with Zero payment to the developer (First task will be for 3 days work to transfer the current working site to a new servers) 5. Milestones after the first one will be more tolerated and finishing in time before the deadline the developer will gain +15% of the Milestone budget fees as Extra 6. Every day after the Milestone deadline will result of 5% decrease of the Milestone Budget . 7. Each Milestone will be in avg Budget of 150$ if your offer is not good or you didn't show possible skills in the conversation interview, you will be eliminated from our shortlist About the Project : The project need someone with full stack skills, the website is under construction already but I need a new developer to take care of it completely , so in short the project works as follows : 1. the webpage UI will let the user do many actions, then these actions has to be sent to our remote servers , they are physical servers, they should get the request and execute some internal work then return back the result to the website with either success or fail 2. the website will then get the result and update the UI accordingly as job done . so the user will experience an immediate javascript change to the UI 3. assume the remote servers received the request and crashed , or even crashed before getting the request, what will happen ? and what is the best design to solve these kind of problems ? If we asked you to develop a mechanism todo such thing in general , without knowing the details for now about our website, what do you suggest ? this is a technical question meant to know the level of knowledge. give a proper answer and show your technical confident and the project is yours . Good Luck .