How robust is WordPress as a CMS?

I’m a former Java/C++ developer who is getting into developing websites…I’m developing a site that needs to display a listing of current seminars (being offered by my client), with a form for someone to sign up for the seminar. I’ve got a page displaying the seminar dates and a seminar registration form (it’s plugin that does “contact me” forms). I’ve gone into the plugin and customized the form to have a drop-down list box that shows a selection of seminar dates to choose from. Here is my issue: my client would like to be able to log-in to the CMS and be able to change the seminars (times, dates, locations, etc.) on the page (okay, no problem), but she also wants to be able to change the list of dates in the form herself, so that she doesn’t have to contact me to do it every time she needs something changed. She doesn’t want (or need) access to any other pages on the site. She also doesn’t want to have to go into more than one “place” in the CMS to add this information. Can I create a template for her somewhere in the CMS that has a simple form where she can input new seminars/dates, etc., and have some code that takes the data and modifies the form, as well as the page listing the seminars (so she doesn’t have to go onto the page directly, or heaven forbid have to go into the plugin itself, which she wouldn’t be able to do anyway with even editor rights)? Can I even use the plugin form in this case, or do I need to create a my own form that gets populated by whatever she enters? At this point, I’m wondering if WordPress is the best tool for my project, or if I should look at Joomla or something else…any advice would be greatly appreciated!