a) to make the wadis more spicy, you can add red chili powder to the ground lentil mixture.
b) to make the wadis in the oven:
1: grease an over proof tray with oil or you can line the tray with butter paper.
2: grease the butter paper with some oil.
3: with the help of a spoon drop the wadi mixture in to the tray and shape them.
4: keep some distance between the wadis.
5: now bake the wadis at lower oven temperatures say between 50 to 100 degrees C for 3 to 5 hours till they get totally dried up and change their color.
6: you will have to keep on checking in between.
7: the time and temperature will vary from oven to oven.