B.M.
My kids are the same age apart. My older son was almost 3 when my younger son was born.
We had the same issues. A couple of things worked. When the baby is sleeping, even though that is your time to get done all the things you needed to do when he was awake (or at least that's what *I* felt that the nap time was for), take some time to spend that time with your older son.
Have special things that he can play with only when you are feeding the baby or when the baby is sleeping.
As for discipline, we used 1-2-3 magic. Since you don't have time to read, here is the quick and dirty explanation. When he is doing something he is not supposed to do, you can count...1-2-3. If he doesn't stop (or do what you are asking), then he has to sit down for 2 minutes (minutes equal to his age). The timer starts when he sits nicely (you can pick a chair/couch, spot on the steps, place of the floor, or whatever.). The first few times might be rough. I think the first time we ever did it, he went into a screaming fit for 30 minutes. The next time was maybe 10 and then now, he just goes to the spot and sits (usually!). When the crying stops, then the timers starts. Once he's done his "time" then he needs to explain why he had to sit out and apologize and say how he might do things differently next time.
Before you begin, you can explain to him that "mommy doesn't want to yell at you anymore" and this is something for all of us to be better listeners and be able to use our "inside voices" or something like that. Explain what the process is. He will probably use the most inconvenient time as his first test. Be prepared to wait it out.
I know this time is hard. It gets better. It really does! I spent the first few weeks wondering what I did to my family by wanting another baby. It seemed to throw things off so much.
My boys are 5 and 2 now and they are great together. Once he sees that his baby brother can be fun, he may start to listen better too. My little guys first smile was at his big brother...just melted my heart.
Good Luck and feel free to ask anything else.
B.