Hi! I am living in China and plays oboe for my school's orchestra. I am looking at the prospects of self-studying the horn cuz I am amazed by this instrument. My school's orchestra is mainly strings+woodwind so we only have 3 brass (2 trumpet, 1 trombone) and no french horn players. Is there any advice on learning the french horn? Also, I would get fitted for braces soon so would braces affect playing the horn very much? Advice on memorizing the fingerings is also appreciated.
I currently do not own a horn. I had just bought a 22-kuai (roughly 3-4 dollars) mouthpiece that is functioning surprisingly well. I will be funding myself on learning the horn so I would not be able to find a teacher. I got into the orchestra after vigorously self-studying the oboe for four months, so I am optimistic about self-learning, but still would very much like some advice!

And also, I had been trying my cheap mouthpiece. I can do some simple tunes like mary's little lamb after ten minutes of practice (the sound is clear, but notes are kind of off-pitch). The buzzing is quite easy, and currently the only problem I got yet is I'm rolling my lips over my teeth too much (sort of an oboe thing, fixed now:-). Articulation on a mouthpiece is also SO much easier than on an oboe reed. But I am struggling with creating slurs (or is it called glissandos?) on my mouthpiece. I also cannot produce sounds above concert pitch central C on mouthpiece, so is there any advice?
I do not expect to be getting on any professional level, so I am looking at a 2290-kuai (about 350 dollars) horn online. Its quite popular online and I watched videos of horn beginners being quite good on this model. But I don't think I'll be buying it anytime too soon. I want to get some one or two months of practice on the mouthpiece first.
Sorry if my English sounds rude or unclear since I am not a native speaker.