Home Build Budget and Project Plan

I have design my house and recently engaged a builder. I would like to establish an accurate and detailed but simple budget including the traditional items like concrete, steel, form-work, windows/doors, ..etc in addition to the kitchen, bathrooms, stair case, light fitting, electrical, home automation, swimming pool, spa, ..etc. The idea is to get an appreciation to 100% of the job and +/- 10 percent of the budget i need to manage to based on land value, affordability and other factors. In the process, I would like to learn the logic of estimation and hopefully the brands / suppliers that I should be able to reach out to. So, I am not just after a report - but a good understanding of the calculations behind each estimate and logic / assumptions / standard cost guides, tools used ..etc. I will need to two key deliverables: 1. Costing Model - at level 1: sq. m rate; 2: by trade /domain; potentially 3: Bill of Quantities for each domain 2. Project Plan - by key phases, activities - highlighting key milestones - and highlighting when do i as an owner need to make decisions / finish homework / select tradesmen ... etc.