אבינו מלכנו כתבנו בספר פרנסה וכלכלה
Once one has requested livelihood (פרנסה), the request for sustenance (כלכלה) seems to be superfluous. The indication of כלכלה is for sustenance of the body (food and drink), such as Yosef said to his brothers "אנכי אכלכל אתכם" (Bereshis 50, 21), or per Dovid HaMelech "השלך על ה' יהבך והוא יכלכלך" (Tehilim 55, 23). When a person has a livelihood then one is able to provide one’s own sustenance. So why do we request פרנסה and then afterwards request כלכלה?
Perhaps one can understand this by referring to the Gemara (Berchos 29b) that some people love their money more than their bodies. Such people are so stingy with their accumulated monies that they would rather go hungry rather than spend money on food.
Therefore, we request from HaShem both items. We request livelihood as normally understood. Plus, we also request sustenance, the ability to control the benefit and sustain ourselves from the earnings of our livelihood (while not spending our livelihood on other things like medicine).
א-ל ארך אפים ורב חסד ואמת
It is known that the concepts of חסד and of אמת can be two differing (and perhaps opposite) concepts. Chesed can mean the setting aside of the power of judgment. Whereas, Truth is a concept of enforcement of the power of judgment, without external factors or favors. Thus, in this petition for mercy the inclusion of Truth אמת is not understood.
It is possible to explain according to the Rashi in the beginning of Parshas VaYechi ועשית עמדי חסד ואמת (47, 29) that these words should be understood as חסד של אמת. This means that when one requests Chesed from another where that other person can not possibly see any benefit, then the granting of the Chesed is a true manner of Chesed without any personal gain.
So it is with HaShem. When HaShem grants Chesed no possible gain can be ascribed to HaShem from the recipient. Thus, when we request רב חסד ואמת, we are seeking the great bounty of Chesed without seeking any reciprocity.
