Yes, check out the social security website. It's all on there.

There's an amount that you can earn without jeopardizing your benefits. I'm not exactly sure but it's about $1000 per month. Also, SS can give you a special trial period during which there is no income limit for a certain time period, where you attempt yo return to work without losing your benefits.
If you find you cannot work, you just go back to being on SSDI as usual.
After the certain trial period is over, you do lose your ssdi.
Of course, I'm speaking from memory, please check it out.