in acknowledging its recipt？ Does it mean "in receiving it (and signing the receiving note) "?

And, does "respecting the succession to Mr Duval" mean "regarding the transfer of your power to Mr Duval"?

Context:

Your letter of 24th ult is before me, and I take great pleasure in acknowledging its recipt - Your remarks respecting the succession to Mr Duval had been anticipated, and were, some time since, substantially presented to Mr Monroe, with such considerations as were in my power in favor of your claims.