If you are working with the standard size gravel, found in most LFS's in a wide range of colors, the botia loach should be fine, but may eat the shrimp. The botias tend to stay above the gravel and hide more in cave settings and under the edges of rocks and drift wood, in plants, etc.
The angelicus botia will get about 5 inches long full grown, so if you wish to keep the shrimp with the loach, I would suggest A LOT of java moss and other dense plants down low along the gravel line, spread over as much of the bottom of the tank as possible. I've seen it done, (keeping both together), but it's not an easy task.
The same thing will apply with the corys, but they are less aggressive than the loach, so the chances of making the shrimp work with one or the other, I'd choose the corys, personally.
With the shrimp, I agree about the slow stocking, especially in a newer tank. Shrimp are extremely sensitive to water quality and it doesn't take much to kill them... just a small ammonia or nitrite spike would do it. I usually advise waiting until the end of stocking before adding shrimp and/or bottom feeders. This avoids the problems that can come with spikes in water parms due to new additions to the tank, and it also allows a natural food supply to begin building in the tank, ensuring that these animals are getting plenty of food without having to increase feedings (and thus, fluctuate water quality).