TheBB
Sure!
In the брать vs взять the difference is truly about perfective/imperfective - thing.
But if you mean the difference between "брать/принимать", then yes again, they mean exactly what you mentioned (take/receive).
There should be something on the forum about it, even I posted something earlier (just too lazy now to look for it myself, but if you can't find anything or still not sure - just post right here again).
And yes, there are 2 different uses of speak/say/talk - говорить/сказать ; говорить/поговорить
And yeah, such overlaps are quite common in Russian, and this is one of the things that confuses non-native Russians most.