The last episode of How I Met Your Mother has not aired yet. The producing team have made mention that the next season, 8 may be their last season.
It hasn't yet.
at birth
Judy Greer plays Royce in the episode "The Wedding Bride" of How I Met Your Mother.
It was called "Intervention"
Hooked - Season 5
The one where Barney gets a cold.
at birth
imdb.com
No
Judy Greer plays Royce in the episode "The Wedding Bride" of How I Met Your Mother.
Doppelgangers (Season 5, Episode 24)
Amanda Peet
It was called "Intervention"
That is Stacy Keibler who played the role of Karina in episode 100 of How I Met Your Mother. She has appeared in numerous other shows as well such as Chuck.
Season 5, episode 17 - Of Course
It was Season 5, episode 12, Girls vs. Suits.
(2x16) Stuff
Hooked - Season 5