The start menu problem has been around, off and on, for some time. Looking for help can be problematic because there are many post start with very early builds of the Windows 10 preview. If you do search, the latest builds were 10168, so be aware what you might be reading.
I see you are using Chrome. Did you set that as a default program or just using it. The Start Menu and Cortana/search all seem to be related and there may be a possibility using a different browser, or at least having it open on the desktop might cause problems. But I have yet to see a good solution for the Start Button situation. Some suggest using a Powershell command, which has worked for some folks, although I do not know why it would be necessary...