Hello,
in that case you can look into this helpfull kb article to see how many hours of videos you can store in this card
http://kb.sandisk.com/app/answers/detail/a_id/2850/kw/hours
so as you can see indeed the FPS can resolve to less videos that can be stored in the card because of the higher quality of videos. to the second part of your question the answer would be that its recommended to format the card after a period of time. of course if you just take 5 pictures there is no need to format the card before and after use.
