Please help figure out a 1900 U.S. census record

I'm trying to figure out some discrepancies. I think I just found the Luzerne County, Pennsylvania 1900 U.S. census record for my great grandfather (Jacob Weber), great grandmother (Elizabeth) and their oldest son (Art) on the FamilySearch pilot site. I included the citation information at the bottom of this posting.

The last name is spelled Weaber on the census, the wife is listed as Elisabeth, and the son's name is spelled "Auther," but those are minor differences. Most of the rest of the data jibes with what I already had. However, I found two discrepancies within the census records that are stumping me. I'm hoping someone with more census experience might be able to shed some light:

1. The census taker noted "age at last birthday" for son Auther as 4/12, even though birth month and year for Auther was shown as Jan 1899. If Auther was born in January of 1899, then his age at last birthday should have been 1 year, not 4 months.

2. Elisabeth's record shows "mother of how many children" as 1, but "number of these children living" as 0. Perhaps it means that Elisabeth was not Auther's mother, but if she was, then this is clearly wrong.

Can anyone help?

1900 U.S. census, Luzerne, Pennsylvania population schedule, Hazleton city, enumeration district (ED) 62, sheet 17, p. 17A (stamped), dwelling 326; digital images, FamilySearch pilot site (http://pilot.familysearch.org); citing National Archives and Records Administration microfilm T623, roll 1432; viewed image of original census record sheet.