It's a very simple and straightforward tame; scary, but simple nonetheless, and honestly quite fun once you get the gist of it. You'll be just fine if you follow the instructions left by other commenters.

Do keep in mind they can bait you with a bellow instead of a roar, only approach if they're roaring LOUD. If they bellow, keep attacking to force them back into defensive stance (sometimes they'll even do the loud roar right after the bellow).

Yes, they can go into boss fights, and yes, they have higher dps and hp than rexes. Their bite is weaker, but the stomp is almost triple the damage of anything a rex can do, and the A.I of tamed Acros uses it constantly, so you'll be doing big damage to bosses constantly with an army of them.

-HydroRex