RE: how srtong are those arms boy-o?
With compound movements you have multiple joints, muscles, and stabilizers assisting with the movement. If one part is too stressed another part can compensate. However, with isolation movements you have fewer joints and muscles moving the weight. If the muscle or the weight gives out, there's nothing else to compensate.
I've never seen anyone suffer a bicep injury with deadlifts, but I have with heavy barbell curls. Likewise, I've never seen anyone suffer a tricep injury from close grips or dips, but I have heavy tricep pushdowns.
There are, of course, exceptions to this general rule and we haven't included the element of good form, but in general, I wouldn't max out on isolations.