It always interest me to read about engineering related post. Good Job sir. However, indulge me as I will like to contribute to your post.
The crankshaft like you have noted is the backbone of the engine. It is the link between the input and output of the engine. The crankshaft is housed in an enclosed casting called Crankcase. This crankcase protects the crankshaft from foreign substances like dust and other unwanted materials.
Aside shielding, the crankshaft needs rigidity i.e. Its motion must be constrained such that it gives only the required rotation and is not allowed to move in any other direction. This rigidity is afforded to the crankshaft by bearings. Together with the crankcase, these bearings called "Main Bearings" support the crankshaft, thus ensuring its balance.
The number of bearings which supports the crankshaft depends of its size, which in turn depends on the size of the engine. Usually all crankshaft will have bearings at each end and the crankshaft will rotate in them.
Aside from end bearings, crankshafts have oil seals at their ends to prevent the leakage and loss of lubricant.
This is great sir. You are very correct and i hope to see your post very very soon. I really wish i had more sp to upvote this comment. Thanks for the contribution