I recently accepted a new part-time (.5 FTE) job and negotiated an hourly rate. When the job offer came it refelcted my total pay 20 hours and was listed as exempt. Concerned I called the hiring director and inquired about the fact that due to my project role my hours could go up or down. The director assured me that they would keep my hours down and adjust my project timelines according to my 20 hour schedule. Shortly after I moved out of state and took my new job I was being sent meeting invites and required training exceeding 20 hours. My project deadlines are equal timelines to my full-time peers. In fact I am to track my hours in a system and I was told after entering my actual hours to take it out and only show 20. This seems unethical at the very least and perhaps illegal. Does anyone one have insight into this subject? I am limited by my current situation to acquire additional project or part-time work and my finances are suffering.

What you are saying are is not inherently illegal. Your starting point is probably to verify that you are legally Exempt. That is a function of your actual job duties and sometimes your industry. There are actually something like 100 different exceptions to the normal rules for overtime, minimum wage or both. The most common exceptions are called the White Collar exceptions. (http://www.dol.gov/esa/whd/regs/compliance/fairpay/main.htm) Many of the exceptions have specific rules associated with them.

If you are indeed legally Exempt Salaried, then as long as the rules of exception are followed, then under the FLSA law you have no legal expectation of either only having to work 20 hours per week or getting additional compensation for working more then 20 hours per week.

Past that you could try making a claim that the representations made to you rise to the level of a contract. Or possibly a Detrimental Reliance claim. But these are both very complicated and difficult arguments that will almost certainly require you to have a face-to-face meeting with a local attorney.

However, you also mentioned an hourly rate. How, in fact, are you being paid?
I saw from your duplicate post that the employer says you are exempt; you didn't include that in this post.