You could cut the peblets in half with a pill cutter, or crush them a bit with needle nose pliers to make them smaller. Otherwise, you may just need to invest in smaller pellets. Bettas can be really picky eaters. It's part of their charm.
Ich will look like sprinkles of salt. A heavy infestation will look like your fish was just sprinkled everywhere, so much that it can look like blankets of salt crystals.
There are a few ways to treat it. The simplest way, especially for a light infestation, is to keep the water heated to 86 degrees Fahrenheit for two weeks. (Even if the spots seem to disappear, continue to heat at 86 degrees for the entire two weeks to ensure all of the cycles of the parasite have been killed.) With this method, you do not need to use medication.
If you use medication, follow the directions on the bottle. I prefer to try to treat illness/disease without medication when possible, but that's a personal choice.
Another sign of ich is "flashing." The fish will dart around and rub against the substrate, plants, and decor.
The best way to prevent ich is to maintain clean, warm water and feed a healthy diet.