I love the instrument and I'd really like to start learning
Then do it. I'm almost 48 years old. About two months ago I started French horn lessons. I have never played a brass instrument before. I'm sure you know that in the brass family, the French horn is seen as the difficult one. I thought a lot about taking up the trombone or the trumpet, but I realized that even if I got a great sound out of one of those, it will never speak to me the way the French horn does. And no matter how frustrated I might get at the French horn, I'll be on a path with a destination that I am really excited about.
So it doesn't matter how hard it is. You love it, you want to learn it, so do it. I'm extremely confident you won't regret it (I'm super happy with being a terrible horn player - for now!)
Regarding the rest of your questions, I have a suggestion that worked out very well for me:
The first thing you do is find a teacher. Book a first lesson and tell the teacher when you're booking the lesson that you have musical training in the clarinet, you want to learn oboe, and you don't yet have an oboe.
The topic of the first lesson is all of your questions. Where can you get a decent oboe, what to look for in a beginner instrument, what kind of reed to start on, synthetic vs cane, pre-cut vs learning to cut your own, etc. If the teacher is reluctant to discuss these things or doesn't provide you with effective help, maybe you don't want them as a teacher and you should look around more.
When I started clarinet lessons I had an old instrument I'd picked up so that's what I used, but my teacher started talking about it and what maintenance it might need pretty early on. So when I started French horn, I did exactly as I suggest and had a first lesson before I even had a horn. My teacher did a great job of telling me where to find "affordable" used horns (the price of entry for a double horn is very high) and also talked to me about things that didn't really matter that much until I'm much more advanced. In the end the cost of a lesson where I didn't learn to play at all was nothing compared to the benefit of starting off with the equipment and the sheet music that would get me going on a solid footing right from the second lesson.
I strongly suspect that a lot of your embouchure from clarinet won't translate to oboe. But what I'm very confident will translate are:
- Your overall lung power
- Your understanding of "fast air"
- The strength and development of your lip muscles
- The greater kinesthetic sense of your tongue compared with someone who has never played a wind instrument
- Your ability to read treble clef and your understanding of music