Which really leads to a subquestion is how do I talk about this stuff and not seem pretentious. Like, I up front disclose that I do not have the answers, I don't pretend to have the answers, I say verbally that I don't think I'm smarter than everyone else. At that point, if I'm coming off condescending, do people suspect I'm lying and just saying that I don't think I'm smarter but I actually do?

I don't know you or how much you know about all the different philosophical topics, but I think you're getting at the wrong problem here. The problem isn't about how not to seem pretentious - it's about stop being condescending because being open-minded in general is the most important tool to learning and discussing philosophy. I mean, maybe I'm talking to the world's super duper best philosopher of reddit right now, the chances are you're being condescending due to your close-mindedness, and when you're close-minded you can't really discuss anything in general.

One way to train to stop being condescending (or generally dismissive of other arguments/views) is to write in defense of the views that you disagree with. Play the devil's advocate and refrain from being biased. Speak as if you're a proponent of the arguments that you disagree with and see how well do you know those arguments and how well can you convince other people.

Even if the people you're talking to are philosophically unread, if they're interested in the subject then you should know well enough to properly explain the subject without being occupied by the thoughts of the other party being too dumb to carry a conversation with you. On the other hand, if the other party is not interested then, as you've suggested, you should be looking for the philosophical ones to engage conversations with. If you're already talking to philosophers, then I believe it's unjustified for you feel that you're smarter than the other person, since you're supposed to know and understand the different views. Be open-minded. If you find yourself thinking or saying "wow you're retarded" before you state your objection, you should substitute that with "I see where you're coming from, but..."

It's definitely the tone that you gotta change. In my experience, it's generally the more knowledgeable people who are more humble, since they can understand the variety of views and arguments. First thing is first though, aside from the tone that needs to be fixed, is to find the people who you deem to be at the same level of understanding as you.