Sounds like it could be a combination of one or more issues. First, make sure "Keep Faces Together" is turned on. If it's off, then when you extrude, it will add extra faces. I don't know what version of Maya you have but for my version it's under the Edit Polygon Menu at the top of my screen.
Secondly, open up the attributes for you split polygon tool. You can do this by clicking on the little box next to the tool. Then look at the options to figure out how many vertices it's set for.
Lastly, open up the attributes for your insert edge loop tool and check it's options as well.
I'm guessing that the problem is most likely that your "Keep Faces Together" is turned off (unchecked).
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