I would predict that your 2 year old will be welcoming if you tell him he is going to have a new "playmate". I did this with my 2 year old and he couldn't wait to see his new brother. I also gave him a little doll that he could play with and take care of just before the baby arrived. He played with this for a few days after the baby came and then became more interested in seeing the baby.
Also, I had started potty training and weaning him from his bottle just before his brother arrived but he reverted back on both. I didn't make a big deal out of it...just wrapped a receiving blanket around him and held him and fed him his bottle like it was only natural to do this (because afterall it is) and he soon didn't need the cuddling like that anymore and was being potty trained and weaned again within a few months.
I did ask that people that wanted to visit and bring a present also bring one for my 1st son (it didn't have to be expensive, just something to show that they appreciated him too). I really felt that he was too young to understand what the fuss was all about. I think that this practice really helped.
I was a single mother who went to work when my youngest was 2 months old so I understand you wondering about the changes with a second baby. It is more work than just one. They don't eat or sleep or go to the bathroom at the same time all of the time. So you will be tired more often than not.
But with patience and a sense of humor and lots of love (and not being too hard on yourself or the little ones) this can be one of your favorite times.
Children learn and imitate what they experience. So relax and be kind to yourself and your children (this is all new to them too) and take the time to enjoy this time..the dishes can wait (or use paper plates).
Today I am a daycare provider and practice the same kind of philosophy...and it works.
And...my own children are grown and the best of friends. And we are all very close.