Fibonacci is the fibonacci sequence. Don't ask me whether it's supposed to be up or down though, I tried and eventually gave up cause my numbers were getting way too big.
Pumpkin Eater is probably for cheating, "cheater, cheater, pumpkin eater"
I don't want to believe this because that's actually really stupid if so but Free Advertising is probably donating to the dev?
1/61 prob has smtg to do with chests opened much like fibonacci sequence. I couldn't tell you how to do it though, dev really needs more/better hints for these achievements imo.