There are two seals on the crankshaft, one large one in the rear (rear main seal) that's really hard to change - leaks cause oil to drip out of the bellhousing and requires a trans pull to fix.

The front of the crank also has a seal, sitting behind the front pulley. Much easier to swap. In addition, there are slightly smaller seals ont he intermediate shaft and cam shaft. Any and all of these can leak.

Although it must be mentioned, if you have seal leaks like this, try clearing the flame trap first - little plastic gizmo in the crank vent tubung that plugs up - then crankcase fumes find the next easiest way out and that's the seals, and they let oil out with them.

It's somewhat unlikely that the timing belt break caused the oil leak, mostly because the engine dies immediately when the belt breaks, and a non-running motor doesn't leak much oil. however, leaks in the seals on the front of the engine often bathe the timing belt in oil, which will cause it to fail in pretty short order.

The cam shaft won't turn 'smoothly' with a wrench, it's going to feel notchy - there are 8 valves it's opening one by one, it's hard to turn as it's pushing a spring loaded valve open, and once the lobe passes center, the valve can push the cam forward.
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'63 PV544 rat rod, '93 Classic #1141 245 (now w/16V turbo)