Not normal or right. Converters do drain back but they drain into the pan. The only place the transmission is open to the outside without a seal is the vent and that's on the top of the case. Something else is wrong. If you buy the car be prepared to spend some cas to get it fixed right.
Adjustability for tuning. Say your combination runs great but pings at highway speeds. You could take some vacuum advance out of it. You may not need or can use 55° at 55.
The AVS2's are quite efficient with their annular flow primary boosters and actually can be tuned quite easily with metering rods, springs and secondary air door adjustments.
The pushrod ends must match the rocker arm adjuster ends. The balls fit into the lifters and the cups are on the rocker end and match up with the ball on the rocker arm. Many stock rockers have cups built in and use a Ball/Ball style pushrod. A ball has to fit in a socket. Think about how that...