1) This site will answer your first questionhttp://www.babypips.com/forex-school/mar…
2) There are only six major currency pairs against the dollar
GBP
EUR
JPY
CAD
CHF
AUD
These are the pairs with the highest volume and the lowest spreads. There are six or eight other “cross pairs” that also have good volume, but the spreads widen to 9 or 10 pips.
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