re: Pork ceviche

Trichinosis isn't really a concern. Freezing kills it. Ask the butcher or head of the meat dept. if the pork has gone through the freezing schedule.
LINK
The salmonella is a different story. Freezing doesn't kill salmonella completely. But if there is contamination in pork you will hear about it most likely beforehand.
Also acid does not kill or reduce the growth of salmonella. LINK
The Prob with raw meat and salmonella is that the bacteria can come from anywhere, and spreads pretty quick. Best bet, get a whole loin or t-loin that is frozen, thaw in refrigerator, cut the portion size, sear, slice then go about making the ceviche.