I don't own a a D100, so I'll skip the lens part, and just offer some insight into the filter question, as I do use a digital, and still do use filters. One can easily enough adjust the image with software, in very fine increments, in every imaginable way. But if, for some reason, you needed to exactly replicate a specific filter, be it a specific grade of compensation or conversion filter, it would be somewhat tricky. There are so-called "plugins", or third party add-ons, for Photoshop and others, which provide these software equivalents.
"Less is not more. Enough is enough. Less is less." David Vestal
"I am always doing that which I cannot do, in order that I may learn how to do it." Pablo Picasso