Verley-Doebner modification of Knoevenagel
In this modification of Knoevenagel condensation, malonic acid (not the ester) is reacted with an aldehyde to yield an alpha beta conjugated carboxylic acid. Pyridine is used as a solvent and catalyst, while beta-alanine (or some other amino acid) is used as a co-catalyst.

There are several ways in which beta-alanine may potentially act as a catalyst (at least in my mind): as a solvent, as a base, or assisting in decarboxylation. I was thinking that beta-alanine acted to donate H+ to the pyridine, which would then reprotonate the intermediate and push the reaction in the forward direction. I am not sure whether this is true.

1. Can anyone please explain the use of beta-alanine? Is it used as a H+ source, or something else?

2. Why can malonic acid be reacted in V-D modification, while only its ester can be reacted in standard Knoevenagel condensation conditions?