I'm not entirely sure why I'm so excited for Windows 10. I couldn't get the Technical release to work, VM or otherwise. I have the computer power, and plenty of RAM, so it shouldn't have been an issue. Yet, coming from Microsoft 'July 29th', and free to boot, I feel very anxious with anticipation.
Yeah, after playing around with Windows RT (which is pretty much Windows 8.1 on ARM, I think) on my Surface, and a bit of the Windows 10 preview, I'm pretty excited about Windows 10 as well. I'm liking it a lot. Though honestly I'm not entirely sure why, because it runs pretty sluggishly on my VM and I haven't bothered to really explore the OS much.
As a side question...in terms of coding for Windows 10...has much changed? Can we still use the same processes as in Windows 7/8? Will we still be allowed to download software from outside the Windows Store? Will the OS still bullshit people and tell them because you are not installing from a "Verified Publisher" that it was probably a virus...and then deletes the installer for you? (Seriously...that annoys me more than anything else on Windows recently...Having my OWN software blocked by my own OS then being told I am not trusted and probably trying to release viruses...)
Answering your questions in reverse order:
I've never experienced the OS deleting the installer for me. I've had Chrome hide downloads from me and not tell me how to find them. But not Windows.
In the Windows 10 Technical Preview, I've installed things using the regular .exe/.msi installers. I don't think I've even used the Windows Store in the preview.
As far as coding things go... I've only slightly dabbled in it. I managed to install one of my games on my Windows RT Surface tablet using the Windows 10 Technical Preview (because you need Windows 8.1+ to make Windows Store builds). And the process I had to use to do that was new to me. But I was doing it for A) a Windows RT device and B) Windows Store application. So I don't know if regular .exe builds are affected by this.