Tips w.r.t land purchase given in this;
1. Get feedback from houses in vicinity or in same line, observe slop profiles or area topography, try to get soil expert or hydrology expert with you w.r.t feedback of area. Actual picture usually comes after soil test but for that you need to buy plot which is not a good decision if you are unsure about filling is there or not. Its better not to go with filling based plot.
2. W.r.t your requirements, I can't refer you a single one:-), might be others in this forum can help you. ALL THE BEST
When you will follow the guidelines of Architect and structure engineer, and execution team will be good, hope you will have a clean, modern and earthquake resistant structure/house..
If you do by your self, materials collection is scattered, you cant get all from 1 source, its impossible near me if you wana have variety and economics both. You can look for any company that can do Turn Key A-Z Project for you, there may be many, but I dont have even a one as per your requirements. You need to be careful w.r.t terms and conditions
Best model will be, you get your work done on labor rate and give material by your self.