Nope, in Germany the only thing you get drenched in plenty of sauce is Schnitzel (breaded and deep-fried cutlet). Something Austrians see as complete blasphemy. I'm afraid there won't be much sauce for your fries in Austria, either. Only ketchup is common. I was shocked when I grew up, startet travelling and watched people munching on fries with all sorts of weird sauces. However, I'm pretty sure that once you've been to Austria, you'll need a lot of a lot more things in your life than just patat oorlog. There may be a lot of things about Austria that can be weird or even downright annoying but the food is amaing. Full stop. Also, since you're a vegetarian but you shouldn't miss out on the opportunity anyway, try to get hold of some vegetarian Leberkäse. (Personally, I only like the real stuff but since that only comes with pork, some people in my family do eat the vegetarian one and tell me they like it.)
Also, sausage stand vocab could be interesting to you. (Some sausage stands have vegetarian options and they are definitely a good option if you happen to be thirsty in the middle of the night.)
One more survival tip for Austria: Our supermarkets are closed on Sundays, Saturday evenings, and any evening really. They usually open between 7 and 8 a.m. and close at 7-8 p.m.!
Survival tips on grocery store hours - THANK YOU! I almost starved to death in Germany on Sunday because everything was closed. We had run out of cash, and couldn't find a bank or a place that A) was open and B) took credit cards. So we turned to the American standby - the convenience store. Nope again. They had tons of soda and candy bars, but nothing that resembled actual food. We went to 3 different convenience stores before we found lunch. We ended up with a bag of cashews, a bag of chips, some type of cheese spread, vodka, and juices. It was delicious, and even more satisfying for how hard we had to work for it. :-)
Expect a similar situation in Austria. Hardly any restaurants take credit cards either. A lot of people here live without credit cards: I'm the best example being 31 and never having owned a credit card. We even have this saying "nur Bares ist Wahres" (it loosely translates to, "only cash is the real thing").