Don't feel bad because there are a lot of women who are in this position. As a former teacher, I love Supernanny. I suggest watching her show and reading her book. She is wonderful. Number one thing to remember here is that you are the parent, and your job is to teach and model for your son on how to behave. (Not that I'm saying you aren't) Just be consistent and firm. Make sure you have clear and concise rules and consequences for breaking the rules...and follow through with them in the same manner each time. He will eventually get the idea that you will not budge.
As for the toys being taken away from him, there has to be a closet/room/storage that has a lock on it, so he is not able to get to it. Remember, you are the parent, and you should not let your child run the household. He joined your life...not the other way around.
If he is coloring on the walls, then put the crayons where he will not be able to reach them such as a locked storage. If he does earn the priviledge (for good behavior) to use the crayons again, then sit with him, so that you have complete control of them. Just keep showing him who the boss is...then let him slowly earn his independence by showing you that he can do it.
Instead of spanking, get down on his level, grab his hands, lower your voice, and use a very firm tone with him. It will work...I promise you. It may take awhile, but it works better than hitting. Use time out. The reason most kids behave badly is to get your attention. They will get your attention in any manner...whether it's a positive or negative attention. Give him a lot of positive reinforcement, and if he's just throwing a tantrum to get your attention, then simply ignore him.
Just be strong...YOU ARE THE PARENT...be strong!!! You can do this. A 2 year old does not rule the house...the Mama does.