to your first question try this adress:
http://www.cisco.com/univercd/cc/td/...ito_doc/ip.htm
this is a detailed description of network protocols
to your second question:
if there are so many connection requests on different ports it could be an attack, but why you are attacked you have to ask yourself...
to your third question:
this is a very long port list there you should find every port and the name of the app using it
http://www.iana.org/assignments/port-numbers
if you like some more information i would try at google e.x. tcp(1938)

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