I am sure this has been discussed before but as of recent what AM station or stations do pretty good in overall ratings and making money?
"Ratings" and "making money" are not necessarily connected. Many specialty stations that are not in English or Spanish do extremely well. Many stations that serve small interest groups do well. Many limited coverage stations that serve a specific coverage area do well, whether AM or FM.
Ratings are really only important for big signal stations that serve entire markets. The rest don't buy and don't use ratings. And smaller local advertisers don't use ratings, don't understand them and don't need them; the best ratings for them is "the cash register".
Also, how about foreign language AM stations?
Lots of them in markets like Houston, Dallas, Chicago, Minneapolis, LA, SF, Fresno, Seattle, Miami, New York, DC, Boston and lots of others do just fine in a language other than English or Spanish.
How do ratings look for different age groups for both?
Most of the stations not in English or Spanish don't show or show very low in ratings. It does not matter. Clients measure results, not ratings.
A station that is AM & FM with same programming, are people listening more to the FM then AM or is listening about even between AM & FM, etc.
We don't know as 100% duplicated programming is nearly always listed by Nielsen as a single station. Translators are never listed alone as Nielsen lists the originating station.
How much does this AM or FM listening vary by market size?
Depends on many factors like total population, number of AMs and FMs doing specialty programming, quality of signal on each, percentage of people in the target of each station, programming skill and quality of each station, percentage of ethnic groups that still speak the heritage language and much more.
Example: a Spanish language station in the New York Market that targets Puerto Ricans specifically will fail as the last migration from the Island of any size ended in the later 1960's and anyone under about 60 won't speak Spanish (although the grandparents or parents may). And advertisers don't want people in their 60's and 70's and beyond.
Ratings are only important for the most popular stations which sell based on metrics such as "Cost Per Point" or "reach" or "Reach and frequency" and which offer efficient delivery of one or more very desirable advertiser targets.