What is the meaning of "ha'Yipalei me'Hashem Davar"?
Rashi #1 (citing Targum Onkelos), Ramban #1 and Seforno: "Is there anything that is too wondrous for it to come from Hashem?" (in this case, regarding childbirth).
Rashi #2 (in Ous, 4:1) and Ramban #2 (citing Targum Onkelos)
: Is there anything that is hidden from Hashem?" (regarding a person's thoughts).
The angel's words were not said in the form of a B'rachah (Refer to 18:12:1:1), they were a message from Hashem (Seforno).
Rashi also cites Targum Onkelos, but goes on to add the words 'wondrous' and 'divided', thereby fusing the two explanations, as the Ramban explains.
When is the meaning of "la'Mo'ed"?
Rashi: It is the same time of year as now (Pesach) next year.
Rashi #2: Refer to 21:2:2:1-3 and notes.
Targum Yonasan: 'On Yom'Tov ... (Pesach).