I had both generations of Gallardo - an 2005 5.0 L140 and a 2010 Balboni LP550-2 with the direct injection 5.2L.
The AWD system in the Gallardo is the same as the R8. It’s a proper rear-biased system rather than a Haldex system like in the A1/A3 series cars. The e-gear gearbox was a Lambo abomination brought from the Murcialego and used in the Gallardo and pre-facelift first gen R8 (until 2013 when Audi replaced it with the DSG).
The 5.0L engine was shared with the C6 RS6, though the Audi version was turbocharged. The R8 V10 first gen and the V10 S6 and S8 used a different V10 as you noted. The LP5xx 5.2L derivatives are shared with the second generation R8 and the Huracan.