Poser is a program that lets you manipulate human figure models in semi lifelike ways.
Yes, multiple dials can Stack on top of each other. You can apply the Height and heavy full body morphs, for example, and they both affect the model at the same time.

With regard to posing, (by which I mean placing the figure in specific positions, i.e. sitting, running, jumping, falling... ) the various body parts are pretty much restricted to bend, twist and side to side. If you have IK (Inverse Kinematics) turned on, when you pull on the foot, the whole body moves. If you don't want this to happen you can turn off IK from the figure menu.

We host a number of poser tutorials that will help you figure Poser out. they are available here. https://www.renderosity.com/mod/tutorial_premium/?section_id=1&page_number=3

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Andy!