Depending on what rule set you use... yes you can die in character creation.

However in the one rule set instead of dying you are severely injured in the second year of the term and do not get skills or any other benefit from that term, and you are kicked out of the service you are in. (That is the one I normally use)
And by the book all skills are random... The player gets to pick which chart to roll the skill on, but it is based on the roll as to what you get...
But were you thinking high(5+), mid(3-4), low(1-2) level (How many terms served before play)
Only the main rule book? or can we use the expanded books.
(When using the expanded books you generally get more skills which is better all round from my experience)
I would like to play a marine (preferably using mercenary book)