1. have your penis stroked/pussy fingered while your ass being licked OR your penis sucked/pussy licked while your ass being finger fucked
Definitely the first one. I love a good rimjob!!!
2. get covered in a very messy mix of foods OR get a pie thrown in your face.
Probably the pie to the face, easier to clean up
3. suck somebody's toes OR have your toes sucked by somebody
Have someone suck my toes. That isn't really a fetish of mine, so I'd rather not have someone else's foot in my mouth
4. make a naked snow angel in private OR go to a sauna with a group of (vague) acquaintances
Snow angel. I'm in a chastity cage, so that might be awkward to explain to others 
5. do 69 lying on top OR do 69 lying at the bottom
Me on bottom. I like the other person to have the control
6. play strip poker with a group of strangers OR go to a sauna (naked) with a group of close friends
Strip poker with strangers. Again, due to my chastity cage, I don't want all my friends to know :3
7. talk on the phone with customer service (or something similar vanilla) while masturbating OR while getting fucked
Getting fucked for sure. That sounds like a fun challenge, trying to control my voice during
8. buy only a cucumber and vaseline in the supermarket OR a large dildo in a physical sex shop
The large dildo. I could always use another
9. have kinky/sexual time with 12 different people at the same time on a single day OR kinky/sexual time with 12 different people, 1 each month
At the same time! That sounds like a fun thing to experience once
10. have your clit/cock head pierced OR get an asshole tattoo
oh my... I guess the cock head pierced. That'd make permanent chastity possible, I suppose, with a PA piercing