No. When this article was previously posted there was an interesting thread on this topic.

https://news.ycombinator.com/item?id=16955549

Edit: I should mention that one can make a rectifier using household chemicals. Caution is still warranted of course.

http://www.hpfriedrichs.com/radioroom/cu-diode/rr-cu-diode.h...

There are some ideas floating about but nothing concrete and reliable just yet.

It depends on what you mean. Typically you cannot get away from HF for the etching process but you definitely can replace the whole process with plasma etch/dep. Full plasma etch/dep fab line isn't really scalable and doesn't create optimal uniformity or layer thickness. But for a project like this, it's definitely doable minus the cost prohibitive equipment.

Not really. SiO2 is pretty inert, it's used as containment for most chemicals.