OTT= Over The Top Its used two ways. As a Comapny name for a Comapny specializing in Toyota and Suzuki upgrades (and some other makes) and also as Over The Top steering upgrades.
In this case its a Company name.
For axle upgrade, Look at Toyota axles becouse of thier wieght, strength (31 spline shafts) and upgrades available (Chrom-Molly shafts). The Drop out thirds a benifit as well in my opinion. Sock gearing, they come with 4.10:1 (manual trans) or 4.30:1 (automatic trans). Factory electric lockers are a great option front and rear.
Under a Samurai, stock Toyota axles will handle 35" tires with no problems especially with any of the suzuki 4 cyl engines (1.3/1.6 8valve/1.6 16valve).
T-case gears is where you will sink some of your cash. 6.5:1 gears for the t-case are the current price point it seems. the factory case is good, but you need to mount it with good mounts and armour to make it last in the rocks.
another way you could go though is with a Toyota W56 transmison and bell housing adapter (the "RingR" and "Lucky-13") kit. that will alow you to use a Toyota T-case with a doubler case. Its kinda your choice, though the Toyota running gear is stronger (but still light wieght) Cost wise, it will be less expensive in the long run using the toyota gear, but its more money up front and more work.
For suspension, YJ springs, Spring over axle and add a anti wrap bar to the rear axle and your set. yor stretching the wheel base, so dont use the missing links, build it for regular shackles.
Steering will depend on the axles used. Factory suzuki, get the Breeze Mfg Over the knuckle steering, it works very well.
For Toyota axles, use any of the aftermarket Toyota over the knuckle steering upgrades or a drop pitman arm. Use a Toyota IFS power steering box, you will need to add a power steering pump, none of the Samurais came with power steering, so use a Tracker setup.
There is alot more I could tell you, but it will just confuse you right now.
Remember, the basic montra for the Samurai is: "Keep it Low, Keep it Light"
No Dana axles, no huge lift and tires, no iron block engines.
Follow that and you will have a light, strong, very capable and fun rig.