What you’ll lose by upgrading to Windows 10

I have windows 8.1 Pro so I guess my conversion will be to 10 Pro. But I feel pity if you can't choose the updates.

Updating windows 8.1 was a pain in the ass for me. Every time I try to update (in cycles of 2~3 months) there is an update that "breaks" the update process and I have to find it, uncheck and try again. A process than could me takes hours (if I'm unlucky). But if you can't update because you are doomed then you are doomed.

I have windows 7. If that qualifies me for a free upgrade, would I be able to receive an ISO of the windows 10 upgrade?

I don't care to actually install it but I would like to archive it on my server so I could install it later, say for bug regression.

Can I request a DVD or is the install only available online?