The best biomes to begin using Wildernether are the Warped Forest and Crimson Forest, as most Nether plants only grow there.
Blackstone is required to craft the Blackstone Stove and Blackstone Scythe, and you will need to find some. They spawn in abundance in Basalt Deltas, or between y=5 to y=31 in other biomes.
The variety of flora that Wildernether introduces are only obtainable via Scythes. Breaking a plant with a scythe does not yield the original plant, (no matter what enchantments are on it,) but has a 20% chance to drop a Wildernether plant, based on the type of plant broken.
Wildernether adds many new foods that can be made in the Nether. Some can be crafted in an Enhanced Crafting Table, but you will mainly be using the Blackstone Stove to cook.