ThomasG wrote: In the spring of 1945 the Soviet armed forces were estimated to have about 665,000 motor vehicles of all types; of these, some 427,000 [32] had been shipped to the USSR from the United States through the Lend-Lease agreement.
As we have seen the real number of foreign vehicles in the Soviet Army was only a half of that:
http://www.1jma.dk/articles/1jmaarticlelendlease.htm
The discrepancy must be attributed to the war-time losses, transfer of vehicles to civilian organizations, Red Navy and NKVD troops, the fact that some number of vehicles arrived after May 1945, time lag between debarkation in ports and delivery to military units, losses en route etc. However, if one takes loading capacity instead of shear number the contribution of the LL automobiles most probbaly will be greater.
Are the trucks used to move troops and guns, or are they used to bring up the supplies to continue the advance?
In both roles as in other armies.
Is there a major difference in how the Soviets use their trucks vs the lend lease trucks, or are the units mixed?
Chassis for rocket launchers, prime-movers for light artillery. These roles require good cross country-mobility, not typical for the most part of domestically produced vehicles.
Given the lack of the initiative that the Germans had in the latter part of the war, does it even matter? If the Germans are too weak to defeat the Soviet attacks, does it even matter if it slows the pace of operations?
As the allready mentioned report of 26th June 1946 says, about a half of all loads carried by the automobile transport fell on the year 1944, when the rapid tempo of operations entailed a great separation of advancing troops from railheads in their rear. So the large number of vehicles was needed to sustain the scale and tempo of operations typical for late-war period.