Q1: I need to a link to a MS doc in either right or left side bar in home page and other pages, where can I find the template or file responsible for this?
You may wan to take a look at the Custom Block plugin, available from Journal Management -> System Plugins -> Generic -> Custom Block.
Q2: On either left or right side bar, I would like to list the editorial team. Do I need to retrieve it from the corresponding table in the database, or is there other way to so?
Ditto. There have also been threads about listing the editorial board on this forum -- a search for something like "editorial board sidebar" should turn them up.
Q3: I need to place the "For Readers" and "For Authors" section in the middle of the home page, any suggestions to do this?
There's no way currently to place block content in the middle of the page via the GUI, but you may be able to do this by looking at the block template code (in plugins/blocks/information), and replicating the code in the relevant central template file. To have this information appear on every page, you'll probably want to put the code into either the header or footer template files; these are found in templates/common, or in lib/pkp/templates/common if you're using OJS 2.3+.