Placement of Adverbs of Frequency

Today we learned to use adverbs of frequency (always, often/usually, sometimes, rarely, never) to describe verbs. Adverbs of frequency are put directly before the main verb: She always goes home after class. If 'be' is the main verb and there is no auxiliary verb, adverbs of frequency are put behind 'be': She is always late to class. If there is an auxiliary verb used with 'be', however, adverbs of frequency are put before 'be': I have never been to another country.

Sometimes violating these word orders makes sentences sound unnatural. For example:
*Always she is late to class.  :-(
*She goes always home after class.  :-(
*We don't sometimes understand.  :-(
*He did never feel so happy.  :-(

But sometimes they don't sound so bad. For example: 
~She always is late to class.  :-/
~She goes home after class always. :-/
~Sometimes we don't understand.  :-/
~Never did he feel so happy.  :-/

So for now, it is safest to follow the rules as we learn the proper placement of adverbs of frequency. But, what do you think about these sentences?

• Children learn never to talk to strangers.
• I think rarely in 2009 were there so many cloudy days in Los Angeles.
• What you lose sometimes is your confidence in your abilities.
• This pie crust dough sometimes is called cookie crust.

Lastly, we added the adverb "frequently" to our list which is closest in meaning to "usually" and "often". What about the adverb "seldom"? Which other adverbs mean closely the same as "seldom"?