Fiction: The 10 years of support start from the day you buy or install Windows 10
There's been absolutely nothing from Microsoft to support the claim that the Win10 support clock starts when you buy or install Windows 10, a claim that has been attributed to an industry analyst.
The new Windows 10 lifecycle and updating requirements look a lot like the old ones, except they're accelerated a bit. In the past we had Service Packs, and people had a few months to get the Service Packs installed before they became a prerequisite for new patches. With Windows 8.1, we had the ill-fated Update 1: You had to install Update 1 before you could get new patches, and you only had a month (later extended) to get Update 1 working. The new Windows 10 method -- requiring customers to install upgrades/fixes/patches sequentially, in set intervals -- looks a whole lot like the old Win 8.1 Update 1 approach, although corporate customers in the Long Term Servicing Branch can delay indefinitely.
Fact: You can clean install the (pirate) Windows 10 build 10240 ISO right now and use it without entering a product key
Although it isn't clear how long you'll be able to continue to use it, the Windows 10 build 10240 ISO can be installed and used without a product key. Presumably, at some point in the future you'll be able to feed it a new key (from, say, MSDN), or buy one and use it retroactively.
Fiction: You can get a free upgrade to Windows 10 Pro from Win7 Home Basic/Premium, Win8.1 ("Home" or "Core"), or Win8.1 with Bing
A common misconception is that you can upgrade, for free, from Windows 7 Home Basic or Home Premium, Windows 8.1 (commonly called "Home" or "Core"), or Windows 8.1 with Bing, to Windows 10 Pro. Nope, sorry -- all of those will upgrade to Windows 10 Home. To get to Windows 10 Pro, you would then have to pay for an upgrade, from Win10 Home to Pro.
Fact: No product key is required to upgrade a "genuine" copy of Win7 SP1 or Win8.1 Update
According to Microsoft, if you upgrade a "genuine" copy of Windows 7 SP1 or Windows 8.1 Update, come July 29 or later, Windows 10 won't require a product key. Instead, keep Home and Pro versions separate -- upgrade Home to Home, Pro to Pro. If you upgrade and perform a Reset (Start, Settings, Update & Security, Recovery, Reset this PC) you get a clean install of Windows 10 -- again, per Microsoft. It'll take a few months to be absolutely certain that a Reset performs an absolutely clean install, but at this point, it certainly looks that way.
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