Assuming we're talking about Version 3.5, you also want to check out the section near the end of the 3.5 Monster Manual about improving monsters by class (also in the 3.5 SRD here:
http://www.wizards.com/d20/files/v35/Improving_Monsters.rtf )
The CR for the Ogre Mage Sor-1 would be 9, 1 greater than that for a regular Ogre Mage, assuming you consider Sorcerer to be an "associated class" for Ogre Mages (i.e., one which works well with their strengths). If not (and I think the MM example doesn't), the Sorcerer level would add +1/2 CR, which I'd tend to round up to +1, though you could add 2 levels instead and still get the +1 CR (and that's what I'd do, considering the PCs are 14th level). Remember that as a Sor-2, the Orge Mage would get +8 skill points (counting Int bonus), 2d4+6 hp, and a familiar (if he wants one), and for increasing from 5 HD to 7 HD he'd
get another Feat (at 6 HD/levels).
For the Trolls, assuming that they're fought as part of ultimately defeating the Ogre Mage, they don't get any CR or EL increase for the Mage Armor and Bull's Strength; that's covered by the increased CR of the Ogre Mage for being able to cast the spells. For their Feats, Trolls (3.0 and 3.5) already have Iron Will, and they wouldn't get any benefit from having it a second time. If Weapon Focus: Claw was replacing one of their other standard feats (such as Alertness), their CR wouldn't be affected. If they were getting it for free, that *might* be worth +1 CR, for a total of CR 6, although they'd do a *lot* better to take 1 level of Fighter (also +1 CR), which would get them +1 BAB, +2 Fort save, a d10 HD, 1 skill point (down from the Fighter's 2 due to their low Int), and a fighter bonus feat (which could be Weapon Focus). Going up to 7 HD wouldn't give them any extra level-dependent feats or ability increases, though if they kept adding levels they'd get an ability incraese at 8 HD and a feat at 9 HD, as per the table in the PHB.
For the Encounter Level, if they're all showing up at once, you've got four CR 6 minions and a CR 9 boss. Four CR 6 creatures would make an EL 10 encounter. Adding a CR 9 boss would roughly bump that up 1, to EL 11. Since you've got a party of 14th-level PCs (and 5 of them at that, rather than the assumed 4), you can expect the players to plow through the monsters without even slowing down. If the goal is make an EL 14 encounter instead, I recommend boosting the Ogre Mage to a Sor-10 (or Sor-5 if you deem Sorcerer to be an "associated class"), raising his CR to 13, and the Trolls to Fighter-2, raising their CR to 8. Remember to add skills, feats and ability scores for the increased Hit Dice.
