It depends on how much alcohol there is relative to other things--sugars primarily, as they are about the only calorific part of most alcoholic beverages once the alcohol is gone (alcohol is the most calorific part for sure). You can use the alcohol proportion by volume (ABV) to approximate a little.
Assuming equal amounts of each:
Spirits don't leave much calorific stuff behind at all after the alcohol is gone because they're mostly alcohol. Alcohol by volume is between 40 and 60 percent in most cases.
Wine leaves a bit more, as there is more unfermented sugar remaining in the beverage you buy, but there's still not a heck of a lot. It depends on how dry the wine is. Alcohol by volume is between 10 and 20 percent mostly.
Beer can leave quite a bit, as many have significant amounts of unfermented/unfermentable sugar. This can be where ABV lets you down for estimating--high alcohol beers are also often high in unfermentable sugar too, so when the alcohol goes you're still left with quite a few calories. ABV can be anything from 4 to 20 percent, with the majority clustering around 5 percent. Lite beers are usually pretty low in alcohol and also pretty dry, meaning low residual sugars too.
A gray area is liqueurs and the like. Many are fairly high in alcohol by volume, but also heavy on sugars.
I should also point out that in many cooking applications, the calories added by the alcoholic beverage are fairly negligible, given the small amounts used relative to the number of servings. Even a Boeuf Bourguignon or Coq au Vin with a whole bottle of wine in it doesn't have all THAT much wine per serving--that whole bottle gets broken down into 6 or more servings, so each person gets less than a glass worth of alcohol-free wine calories. That probably averages something like 40 extra calories per serving.
I don't think this has a single answer: The amount of alcohol would depend on the alcohol content of the soaking liquor or liqueur, soaking time, temperature of chocolate, and how thick the strawberry was.
I suspect uncut strawberries would take at least several days to fully absorb alcohol and reach equilibrium, but the surface should take up alcohol fairly quickly. If they are cut up, exposing the more porous interior, I imagine an overnight soak would be sufficient to reach maximum alcohol content. The enormous, bloated mutant strawberries you sometimes see at stores could take considerably longer than others to absorb their maximum alcohol.
Alcohol is much more volatile than water, so the immersion in warm, melted chocolate would remove some alcohol, but once the chocolate cools, it should trap any remaining content.
The flavor of alcohol is easily masked by other flavors at under 20% content; this could explain why your friend didn't taste it, but you did. It's quite possible the strawberries packed a sobriety-busting punch, but it was disguised by the chocolate and fruit tastes.
Best Answer
Harms? Meh, that's silliness. You can make your own fizzy water if you're so inclined. Sodamakers.
If you really don't want fizzy, then just substitute still water in any of the recipes in a search for Virgin Mojitos. Choose recipes that use soda water, club soda or seltzer water, not ginger ale. Ginger ale adds flavor, you want recipes that stand without that flavor.
EDIT: Just to be clear; soda water, club soda or seltzer water are all just water, injected with carbon dioxide to make bubbles (carbonation). So by substituting regular water for soda water, club soda or seltzer water all you're losing is the "fizzy". (Club soda may have a tiny amount of something like baking soda to neutralize the decrease in PH caused by the carbonation, Slate gets further into it, but for all practical purposes, they are all just bubble water.)