Chana dal vs dalia/pottu kadalai:
My mom always uses chana dal/bengal gram. Many of my friends use pottukadalai/daalia/fried gram. While using pottukadalai has the convenience of being ready to use (don't have to fry like chana dal), I personally prefer toasting the chana dal in a tsp (or even less) of oil - I feel it adds more body to the chutney, and the protein may be higher. Feel free to use whatever works for you.
Ginger and Tamarind:
Using ginger, a very small piece, adds an amazing taste/flavor to the chutney. Try it, and your guests will ask you for the secret ingredient that makes your chutney so special!
Tamarind is typically not used by Tamil people in this chutney. I learned to use it from my Telugu friends, and love the sourness, not to mention it improves the shelf life. That said, the bible of tambrahm cooks, "Samaithu Par" (Cook And See) by Meenakshi ammal, recommends using a dash of lemon juice which I assume is for the same purpose. Either way, the chutney will taste better and last longer.
I've been called a chutney snob, and as such, I cannot emphasize enough the use of fresh or frozen coconut. Desiccated coconut simply does not cut it. When using frozen, make sure to set it out about 30 minutes or so to thaw at room temperature. Defrosting in a microwave will make it go bad quickly, because it's basically cooking it and coconut does not tolerate heat.
These are tips I have incorporated over 25+ years of eating and making chutney, and have gotten many compliments on my coconut chutney, whether fresh or frozen coconut.
Other optional ingredients:
Add a small quantity of fresh cilantro or mint, for a pop of color, and flavor! I always do, if I have these on hand.