Last but not the least, what’s the way to delete a keyframe on a particular point in the timeline without breaking all connections?  (and by the way, where do i need to look to see where in the timeline has anything been keyframed at all)

By default, when you have something selected with attributes in the channel box keyed you should see a key tick on the time line where there is a key.
If you don’t see any ticks, double check your animation settings (the little box next to the auto key button) I usually have the Key Ticks set to Active and crank up the key tick size to 5 so that you can see them better.
To quickly delete a key you can click select the frame in the time line and hold down the RMB and select Delete. To remove all keys on an attribute, select it in the channel box and hold down RMB and select “Delete Selected”.
These are the rough and fast way to make edits to your animation.

The way to make real changes to your animation is with the Graph Editor
In it, you will be able to see all the keys on a given object (or group of objects).
There is lots to learn about the Graph Editor...so I recommend first going to Maya Help.

All the best with it.
~Ben