@Hoang Bui
As an inexperienced investor you are in need of a contracting lesson from those who have done it successfully before. You need to be able to control what is being bid and how it’s being bid. Starting with a detailed scope of work that breaks down all labor and materials required to complete the job, will make sure any general contractors you get quotes from will be bidding on the same exact work. I did remodeling for several years and was always happy to see when a prospective client I met with had a firm grasp of what they wanted to do and materials they wanted to use because it meant they had actually put some thought into the project.
You can google Remodeling scopes of work to find lots of examples and you can cut and paste ideas to create your own. Anything not specified in the contract or the scope of work will be open to interpretation by the contractor and not usually to your benefit. An inexperienced client will claim ignorance when something they thought was included in the fixed price turns up as an extra. Clients need to think thru a project completely or they will get hit with change orders that will be at a higher margin than the base contract.
An easy way to have your contractors price materials for a project is to give you a retail $$ allowance for the item you can choose from one of their preferred suppliers or any where else you want to find it. An example might be an appliance pkg where an allowance of $1200 for a refrigerator, $800 for a range, etc, or with flooring it might be a square foot allowance of $3.50 for porcelain tile.
As far as draws go, try to make sure that any schedule of draws actually corresponds to the way the construction is being done. It’s ok if your paying for something like cabinet materials before they are installed because they often have to be ordered ahead of time, but I would not expect to pay early in the draw schedule for labor that will occur halfway or at the end of the project. If you have the time, ask around at a Real estate meeting or local online group and see if there are contractors getting good recommendations and go see jobs they have completed or are Actively working on. Legit contractors have lists of satisfied clients who are happy to talk about their experiences.