1)
What is "Lishmo'a b'Kol Todah"?
1.
Rashi: This is like Lehashmi'a (to make heard). Radak - also "Lashmid Ma'uzneha" (Yeshayah 23:11) is like Lehashmid. I will go to the house of Your Mizbe'ach to thank in a loud voice in front of a congregation of Kedoshim, for Your Chasadim and saving me from every affliction.
2.
Malbim: The primary thanks is that I can tell Your wonders. Via this, people see Hashem's greatness.
2)
What are "Kol Nifle'osecha"?
1.
Rashi: It is Hallel. It has [thanks for] the past, for Gog [and Magog], of the days of Mashi'ach and l'Asid Lavo.
2.
Radak: They are the wonders You did for me at the times of my afflictions.