a one block wonder is a kaliedescope quilt- the blocks are usually either 10"or 12" blocks-and it takes many to make a quilt
you can google (or search here in pictures) for one block wonder quilts
as for squaring up your quilt- if you square up each block as you go along your quilt should be pretty square when it is done- so not that big of a deal
if after quilting it is wonky you might have to do some squaring--but it is usually not that much-
blocking a quilt is really only necessary if you are entering it in a show and need it to be perfectly square to hang- seldom are bed quilts actually square...just close- and as long as you keep your blocks neat-and trimmed/squared as you go you will be fine=
don't stress yourself out with details that are not that important- work at achieving (perfection) knowing that no one is ever really perfect.
after you have finished a few quilts you might decide you want to enter a show---at that point you will have this figured out-