Page Bleed:
Printing industry term for a page on which the printed (inked) area does not have the usual blank (inkless)margins. In all printing processes, a narrow space must be left along the paper's edges for it to be gripped, and to prevent printing ink/toner from going on the ink-free/toner-free parts of the machine. Bleed printing is more expensive where it requires oversized printing plates and/or paper (from which inkless margins are trimmed off to leave only the inked part).
definition: http://www.investorwords.com/10446/PageBleed.html
Margins:
The margin — top, bottom, or either side — is that usually empty space between the trim (where the page is cut) and the live printing area (primary text and graphics) of the page. Sometimes headers or footers may be placed within the margin area.
http://desktoppub.about.com/cs/basic/a/margins.htm
Gutter:
The inside margins or blank space between two facing pages is the gutter. The gutter space is that extra space allowance used to accommodate the binding in books and magazines. The amount of gutter needed varies depending on the binding method.
definition: http://desktoppub.about.com/cs/pagelayout/g/gutter.htm
Many of the tools within InDesign are very similar to Illustrator. Once you have a good understanding of the Adobe software the functions are very quickly learnt.
Overall:
Having already used In Design for a year it was a good chance to refresh my knowledge on the program but not much has changed from CS4 - CS5 in means of difficulty.