Welcome to Librarium Online!
First and foremost in consideration is that I'm moving from 40k to fb and have bought nothing but the rule book and the OK army book.
Chose OK cause i like the look of them as well as the fluff and they seem fun to play cause of high movment and fun on the charge.
Slaughtermasterlevel 4 wizard with lore of the great maw and talisman of preservation 
Bruiser with BSB, iron fist, and heavy armor 
Firebellylevel 2 wizard with lore of fire and hellheart 
Ogres x6 withfull command and iron fist 
Ogres x6 with full command and iron fist 
Ogresx6 with full command and iron fist 
Mournfangcavalry x3 with full command, heavy armor, iron fist, and dragonhide banner
Mournfangcavalry x3 with full command, heavy armor, and iron fist 
Main concerns i have with the list :
----Is it legal? (i think i understand percentages correctly)
---- Am i using magic items correctly?
---- I'm aiming for my bulls to head up the middle with leadbelchers on supporting flanks and mfcs as my main flankers
---- Is it ok to run 3 squads of 6 bulls with one character in each? viable strategy? firebelly work better with leadbelchers?
---- Not to sure how to have my TT support my army mainly picking it for cool look (would stonehorn work better with my mfc?)
---- Finally I like the dragonhide banner but is it worth it?
Rip my list apart if need be and i still have some points left over for magic items on bruiser.
Welcome to fantasy!
The list looks pretty sound except your core, imo. At this points level you'll be going up against (probably) 2+ hordes of pretty nasty units any enemy can muster. Against those kinds of things, it's imperative that you have a unit that can hold up these units while your MFC get into position. I'd say either A) take a bull horde of 19 Ogres with all your characters in there and just be careful with it, a unit of 10 Ogres and a unit of 8 ogres with FC each and a few chars smattered across each or C) a unit of 10 Ogres and 6x IG's with FC in each.
Option A) would probably be the best bet just to give you staying power and damage, but is susceptible to nastier spells, redirectors and the sort. This being said, the lead belchers should be able to deal with redirectors, though turning them into a unit of 8 with a musician, or 7 with a musician and 2x single sabertusks for redirectors + warmachine hunters are options worth consideration. They should be advancing 6", firing and eventually supporting your other units in combat through flank charges, or holding up enemy flank chargers.
I know it wasn't in the listed above options, but if you just max your core in IGs, you'll get much more use out of that fire belly's flaming attacks, too, as they'll give the firebelly a chance to cancel any regen you come across 1st for the IG's to pulverize. I know I've thrown a lot out here, but if you have any other questions, I'll try to post back soonish! TT goes really well with the IGs, as you tend to not have to worry about those expensive guys dying before getting their "2 cents" in....problem is that it tends to get shot to pieces by mundane troops and cannons (in my experience). Remember that it's perfectly acceptable for them to be hovering 1" from an enemy and NOT charge in to ASL support, while guarding your IG's flanks and shooting at other juicy targets!