1) This is an internet archive version of that article (not great to read in this format unfortunately):
Another similar idea here (this example shows data for Primary Contact, but the principle is the same):
blogs.msdn.com/.../showing-related-information-in-a-crm-2011-form.aspx
2) No, you can easily shows values from a parent record in a VIEW, not on a form. For a Form, see (1)
3) This might help: blogs.msdn.com/.../deep-queries-for-subgrids.aspx
Technically unsupported, but essentially steps for how to create a grid on a form using any query you like, so should be fine for parent account to be included. Not sure if you can do an OR on this (records related to this Account OR the Parent Account). you may have to have two grids, one above the other.
4) In advanced find, you usually have to start at the bottom. So you could list all (child) Accounts which have a Parent Account which has some property or other (or is related to a specific type of parent or child records, which in turn may have some specific properties). In other words, you can't find the parent accounts and ask it to list the children, you go look for the children based on their relationship to a parent you are interested in.