1) See if a bicycle maintance course if offered where you live. I took one. for a bit more that a overhaul of my bike + 5 evenings I learned how to care for my bike and enjoy it.
2) The pedals "screw" into it. BB = bottom bracket. Usually you buy a sealed one, but old school BBs could be taken apart and ball bearings and grease replaced. both the front and rear hubs will need to be maintained too. My guess is that the one with your bike was cheap so it will wear out soon. To remove it you need special tools and if you screw up you will strip the crankset.