Not sure why you would need a kit, unless you're just referring to the grinder. I do it myself during the summer. Coarsely grind whole beans, let them steep at room temp for a day, strain, add ice, enjoy.
This. Kit's unnecessary, but not a bad if you got it as a gift. Probably has a good strainer.
Started doing cold brew (iced) last summer - great stuff. Use good fresh ground coffee and good water. I prefer giving it 2 days, but 1 day is still excellent. As Belly said - throw grounds directly in water, mix, let sit for 1 day (12 hours at least). Strain, pour, prepare (cream and sugar), ice, drink, repeat. Make coffee ice cubes if you don't like it to water down. Best iced coffee you'll find and much cheaper/easier than going to the shop every day.
French press is an okay strainer, but not the best. Not a fan of heated cold brew - French press, pour over are better for hot coffee, imo.
Enjoy!