1: Get a set of calipers and measure. Across the smallest part of the lobe gives you the base circle. From the tip of the lobe to the far side gives you the max height. The difference between these two is lift. There may also be markings on the cams you can Google.
2: Yes.
3: Once the new cams are fitted check your valve clearance and adjust to suit. If you have two sets of shims you'll probably find you can swap them around to make it work, but in any case you can't avoid measuring.
4: Yes, you can swap the entire smallport head onto your bigport for even more sikness.