Because the LaserJet 1015 was discontinued long before Windows 7 reached its peak, HP did not release a dedicated, boxed software package specifically labeled "Windows 7 64-bit" on their main support page for a long time. Instead, they utilized a "Universal Print Driver" (UPD) strategy.
No. The driver architecture must match the OS. A 32-bit driver will not even install on a 64-bit system. Hp Laserjet 1015 Driver For Windows 7 64 Bit