If you have just performed a completely clean install AND ran Kaspersky, then you should be malware free. If you really suspect malware then yes, by all means, open a new thread in the appropriate forum.
I do not know what you mean by backing up a current installation as an ISO file. An ISO file is used as a special type of file that contains the fundamental aspects of an operating system so that you can use that to install the OS into a computer, not as a type of file that is designed to store an entire installation. To create a back up file of your installation, many people use Macrium Reflect, it is a good program that gets good reviews.
Another thing I don't understand is that you said that you just performed a clean install of a non-insider build but you are currently running an Insider build, is this correct? So you installed the current retail build of Windows 10 1803 (build 17134.137) and then went through the process of updating your system to preview build 17704? This build is awesome with many new features and bug fixes. Expect that build to be around for a few weeks because a lot of work went into it.