For the placement of forms its up to you to decide how far you want to take it. You can take keyboard keys down to 1/8ths or 1/16ths if you really wanted or you can take it down to 1/2, 1/3, 1/4, etc. It's up to you to decide.

For the orthographic study it depends on how complex the object is. If it's really complex you would need 2/3 (side / top / bottom) but generally only the top and side is needed to construct the object. It's best to look at the mouse demo for how to transfer orthographic plans to the object. The reason you don't need to do more than the top and side view is because when we draw the object at most we will only ever see 3 sides of it because we are fitting the object inside a box.

However, I didn't understand the part about the beer can/tea pot and the enclosing box and need more clarification.

For your question about the beer can / tea pot on lesson 6, If you take a look at the difference between your sunscreen tube and the beer can you can see that there is no box around the beer can while there is a box around the sunscreen tube. You always want to have a box around the object because it allows you to be more precise by allowing you to subdivide the box so that you can pin point specific areas. When you don't use a box and just use ellipses instead that would be more akin to pure observational drawing rather than construction drawing which uses both observation and an understanding of how the object sits in 3D space to make the drawing appear 3D.

Hope this clarifies things a bit and if you have more questions I'd be happy to answer them.