I am going to do clean install. Fingers crossed.

Created iso using MCT and its size is 3.38GB but the iso file from direct download link is having 4.079GB. What is the difference? Is the iso created by MCT corrupt?

Today I installed Windows 10 pro on a newly bought Hard drive.
1 .I had Windows 8.1 Pro DVD. Clean installed and activated it using the key.
2 .No drivers installed, no updates,...

Same here :/
My system taking exactly 20seconds but if restarted, it will take more than a minute.