Right, the fact that an attacker would “reveal his hand” by making a DoS attack is the basis for the DoS-hardened difficulty mechanism.
Right. There needs to be at least one honest party with fast enough hardware (specifically, no slower than A times what an attacker can do).
This is the current plan. We want to build a state-of-the-art commodity VDF ASIC—in collaboration with Filecoin and others—to get a reasonable maximum advantage A. The ASIC would be optimised for squaring modulo a fixed 2048-bit modulus (this is the RSA setup for the Wesolowski VDF).
We are considering outsourcing the hardware design and manufacturing to Obelisk (see their launchpad service), the same company that did the Sia hardware.