#1 - Search for "pumpkin recipe" here on HBT and you'll find plenty. Learn to love the search feature!
#2 - Don't "dry spice" in the fermenter. It's not sanitized and you won't get your best utilization from your spices. You'll want to make a tea or a tincture. To make a tea, the spices need to soak in hot water to release their aromatics and then cool before adding to the fermenter. Ideally, you'll want the water boiling for a bit with the spices in it to make sure it's sanitized - a lot of brewers use coffee percolators to make spice teas. To make a tincture (which many people mistakenly call an extract), soak the spices in alcohol overnight, then add to the fermenter. Be sure to use at least 80 proof (40%ABV) alcohol like vodka to sanitize the spices properly. Careful selection of your liquor can be beneficial to flavors (for example, whiskeys work very well in Scottish and Irish ales)...a nice spiced rum could add some lovely caramel flavors to a pumpkin ale. As for your spices, the "pumpkin pie" recipes call for something along the lines of 1/4tsp each of cinnamon, clove, ginger, allspice, and nutmeg. A "pumpkin pie", "apple pie", or garam marsala blend could work instead. For an extra twist, you might want to consider other "pastry" spices such as mace, cardamom, white pepper, etc.