People of all levels are welcome here. As mixedmath points out, amateur philosophers may find it challenging to ask questions initially because they lack the understanding to focus it enough to be a good fit here (often newbie posts can read as just a rambling of ideas that lack any real coherence), just as they will have less experience with which to answer questions as thoroughly as others. That said, the problem isn't exclusive to new users or beginning philosophy students; take myself for example. I have a degree in philosophy but I only specialize in specific areas, so when it comes to answering questions outside my expertise I will almost always be outclassed by the resident expert in that area (mixedmath for math, rex kerr's keen on physics and logic, DBK's new but he seems to be right on with the history of philosophy and philosophy of science, michael dorfman pretty much everything lol, etc.). But that doesn't mean we shouldn't try to answer though; we may very well have insight that the expert may not or that they might otherwise glaze over.
So when you ask whether the community is a good fit for amateur philosophers, the answer is a resounding YES!
The great part about being here is not merely reading questions and answers, but the process of going through and creating an answer yourself — that's where you really learn fine-tune your knowledge. It's one thing to have an idea in your head; it's another thing entirely to write it down in an accessible manner and backup your claims with evidence. I find myself diving back into old philosophy texts and re-familiarizing myself with the material all the time, making sure that what I believe is wholly justified and defensible. In fact, amateur users who take the time to answer questions stand to learn the most here, because in many cases they might have to start from scratch to answer a particular question that interests them, and by doing so they learn a lot along the way. :)