As a woman, I'd advise you that, if you take some of the above advice, you will fail and probably be the subject of much gossip in the best case scenario.
Paw tattoos are common. Sure, ask about it - but don't read into the answer. Those of us with very active, sexual imaginations are obviously going to fantasize about all sorts of scenarios. That's when you have to be the most cautious and use your common sense. If you say anything to this woman about fucking dogs, you're going to turn her off - even if she's totally 100% into fucking dogs. On the list of the most creepy psycho thing a guy can do/say to a woman, that's waaaay up there. I would NEVER want to fuck/date/whatever someone who, out of the blue, alluded to or flat out talked about wanting to see me fuck their dog (and that's something I'm into). For most women, it'd be like if someone walked up to you and talked about wanting to piss all over you or tie you up and suck your feet. Want to send this girl running for the hills, talk about her paw tattoo and "cupcake" while being kinda creepy (she'll google it or ask a friend - then you're fucked). This just isn't something "normal" people talk about in public to relative strangers, and it'd be a huge indicator of some underlying personality or communication issues. Is that what you want her lasting impression of you to be?
You do not deserve anything from this woman, let alone straight talk about sexual fantasies. It sounds like this girl is an acquaintance who is paid to smile and be nice to you and customers in general. Maybe it's more than that. Trust me, there's a 99% chance you will never know if you creep her out. If you're really into her, ask her on a date. Don't be overly sexual and weird. Try not to fantasize about her and definitely don't tell her you do it until later down the line. Be kind and genuine. If you're clicking, I'm sure you'll eventually have some regular sex. Maybe throw in a little kink after a few times. If she seems sexually open-minded and you want to start being slightly less discreet - fine. But, until you do that, you'll be at best a creeper and at worst, someone she's afraid of and tells all her friends, parents, boss, etc. about "that weird guy".