Hi,
It's interesting that you want to become a registered agent to help inventors patent their inventions. That's pretty much what I am doing now. I'm a registered agent and I worked at a law firm previously. I've since left the firm to pursue other interests. On the side, I do exactly what you listed in 1.
I'm sure you will have no problems passing the agent exam, but I just want to point out that passing the agent exam isn't the end all and be all of being a patent agent. Before I worked at a law firm, I spent a brief stint at the USPTO as an examiner. I passed the agent exam while I was an examiner, and I went into the law firm job thinking I knew how to write an application and prosecute an application. After all, I passed the agent exam! But once I got there, I found out I didn't really know about representing a client or writing a good application. There's the stuff in the MPEP and then there are the "tricks of the trade". My point is that in order to be a good agent, you'll need to acquire some experience. I'm quite sure that no attorney or firm would hire you, even part-time, if you don't have any experience under your belt.
So unless you find a way of working or training with an experienced attorney or agent, I think your 2 goals might be out of reach, particularly goal 2. You can take the plunge and represent clients who are willing to have you represent them a la goal 1, but you run the risk of malpractice if you screw up. You have to keep in mind that when you represent a client, you are taking their IP, which could potentially be worth $$$$, into your own hands. A screw-up by you, the agent, could mean unrecoverable loss of the IP that the client put in your trust. So before you think about helping inventors patent their inventions and charging someone for part-time work, think about getting some experience. That's just my 2 cents.