As the title says, and preferably no soy, don’t feel like getting man boobs.
Any its just protein. Doesn’t matter
Any of these. That article also explains what, why, and when for different types (whey, casein, hydrolyzed casein, etc.)
Not totally accurate. Plenty of cheap-o brands, and more than a few more well-known brands, have been caught amino spiking - basically lying on the label and claiming X amount of “protein” while counting anything from gelatin to individual aminos as part of that total. This article talks about it and a quick Google will bring up a list of companies that’ve been busted and/or have ongoing lawsuits about it.