I'll see what I can do here...
Re. profession --> it's pretty much up to you how much the second prof. affects your character. If you would have a ranger as a secondary, you would be able to use the 3 "secondary" attributes of the ranger: Marksmanship, Wilderness Survival, and Beast Mastery. You would not be able to use "Expertise," which is their main attribute. You will not be able to use ranger armor (but you can use any weapon you want... even if its not warrior or ranger based), the armor you can wear is based on your main profession. And yes, you can have a pet with a Ranger secondary.
Re. attributes/skills --> Yes, the attributes are basically just bonuses that your character gets. The strength of a large majority of skills is based off of the points that you put into attributes. (I.E. A sword attack would maybe do +10 damage with 2 sword mastery, and +20 with 12 sword mastery)
Attributes - cannot be "activated," they are always turned on.
Skills - they must be activated whenever you want to use one... but some enchantments are always turned on after you use them initially. Most skills are either "once-and-done" when you use it, or have a certain duration (normally about 5-60 seconds), but like I said earlier, some are maintained from the time you use it, to the time you die or switch areas (mending, balthazar's spirit, faithful intervention to name a few)
Hopefully that answered everything, sorry it's kind of poorly laid out... also check out
http://gw.gamewikis.org/wiki/Main_Page
for a lot of answers to pretty much anything related to the game.
Have fun!