I'm using a TP-Link WDN3800. I didn't bother with installing the software. Just downloaded the Atheros drivers. It connects quickly, and stays connected.
Motorola and Arris are generally good bets. With Comcast, I'm using a Arris CM820 that I bought refurbed off ebay a few months back, for a whole $30 shipped.
Probably your best bet is going to be fixed wireless. The hard part can sometimes be finding one that serves your area, as they tend to spend little on advertising.
Instead of using NFS, I would stream the disk image over an SSH tunnel from the VPS. Here's a guide on it, https://www.pantz.org/software/dd/drivecopywithsshanddd.html, though searching for "dd over ssh" will find other examples.
Depends. If the provider offers IPMI or remote console access, this is do-able. You don't even need virtual media support for it. You could have GRUB boot a live OS (run from RAM) using memdisk. Then from within that, overwrite the disk. I've done it in the past, where I had GRUB boot up mfsbsd...
We've had decent luck with Dell Precision. But, for the most part we opt for Supermicro systems built by a local vendor, as they offer more for the money, and quicker support.
Having lived in places with a bunch of ISP choices, it's not always great. Only one bothered to offer faster and faster speeds, the local cable provider. Local telco reduced their speed offerings down to 3Mb (they had ADSL2 DSLAMs so they could offer up to 24Mb), and the other local ISPs...