If you can get your hands on a USB keyboard or a PS/2 to USB converter you can type with a KB (I'm a PS3 player as well).
As for the jobs, yeah gladiators and paladins are tank roles. The tank role is keeping all of the enemy attention on you because tanks have the highest HP and defense. While they don't do as much damage, they can take much more than any other role. Marauder/Warrior are tanks as well (the axe job).
As for some tanking pointers, flash is your best friend as a gladiator. The enemies have to be within a certain radius of you for it to hit, otherwise it does nothing but use your MP. Usually if you pop 3 flashes as soon as you pull a group of mobs you'll keep the aggro/enmity/hate/threat (and whatever else people will call it). Many classes/jobs also have skill combos, such as the Savage blade combo for Gladiator and Paladin. When you use Fast Blade a moving dotted line will appear around the perimeter of the Savage Blade icon, when you do Savage Blade with this indicator it will do more damage and increase the "hate" the monster has on you more. If you do Fast Blade then Riot Blade, the latter will recover MP for you (which is imperative if you need to use flash again while in battle). And while this next point isn't necessary, marking the targets to attack will really help you hold the aggro in some cases as well. If you hit the square button on a target you can select "mark" on the menu. It's a general consensus to fight the marked targets in numerical order (1, then 2, then 3, etc) and it can save a group and make your job easier. (You can also make a macro for this to do it faster, such as "/mk attack1 <t>" [without the quotes]).
It's kind of hard to explain things through text on a forum without being overly complex. I'm sorry if my paragraph was. I hope that dungeon experience didn't ruin the game for you, there are plenty of us who are willing to help new players learn. But there are just as many who would rather insult for not knowing the role yet, and label the player for being "bad". Try joining a free company on your server, there are bound to be people who are willing to help you along and show you the ropes and whatnot if you really want to play gladiator.
Otherwise all I can say is maybe try a different class. You might not like the equipment as much, but you might find the playstyle more fitting to your own.