Unless that changed with the 1.9 patch, or my save is bugged, they don't vanish until their duration is over. They definitely do not count toward summon limit. They also are not impacted by the atronach abilities. They seem to be 'different' than other summons.
On another note regarding the consideration for masculinity, the counter for the female wolves is they tend to get more benefit from the Agent of Dibella ability (seems to be more men than women as opponents... but that may just be experimenter bias) and Lover's Insight from the Black Books. This would equate to a 20% increase in damage v. male opponents.
Unless that changed with the 1.9 patch, or my save is bugged, they don't vanish until their duration is over. They definitely do not count toward summon limit. They also are not impacted by the atronach abilities. They seem to be 'different' than other summons.
On another note regarding the consideration for masculinity, the counter for the female wolves is they tend to get more benefit from the Agent of Dibella ability (seems to be more men than women as opponents... but that may just be experimenter bias) and Lover's Insight from the Black Books. This would equate to a 20% increase in damage v. male opponents.