New in tanking and need advice

[Azurus]

I have been a ret from the start till lvl 80 and only few days ago i dueled to Prot too, i need to know some facts about the gear and gemming

1- deff rateing : what is the cap
2- what should i gem for first, dodge , parry or block , i know i have to increase them all but which one of them is more important to start with, and what is the minimum needed and the cap for each one of them
3- what are the best enchants for every item

finally i have a major problem with mana , i use devine plea whenever it is on CD and still i run out sooo fast especialy when i am taking out multiple targets so is there something that i am missing or is the specs done wrong
The World of Warcraft Armory (http://eu.wowarmory.com/character-sheet.xml?r=The+Sha%27tar&n=Azurus)

any advice from the good tanks out there will be appreciated

[Thaak]

http://www.tankspot.com/forums/f200/41907-frequently-asked-questions.html

http://www.tankspot.com/forums/f63/40003-diminishing-returns-avoidance.html

http://www.tankspot.com/forums/f97/39462-wotlk-tanking-gear-list.html

The search bar isn't for looks.

[Zothor]

Seriously, search bar. there are a million topics on just this. But just quickly:

1) You're specced terribly. Research paladin tanking specs.
2) If you're keeping Divine Plea up and going oom, it's because you either aren't buffing Sanctuary on yourself or you aren't Judging Wisdom. Do both.
3) The rest of your assumptions are all wrong. Do some research, this is all covered here. There IS no defense cap, and you shouldn't be gemming for anything you listed. YOu can't even gem for block if you tried.

Homework, son. Tanking is NOT for the lazy. Lazytanks are bad tanks, it's a demanding role.