I find Gaelic and Welsh fascinating from an aesthetic point of view, but found them always much harder to learn than the Germanic and Romance languages I'm familiar with.
Is Gaelic regularly taught in Scottish high schools?
It is, especially in the highlands and formerly Gaelic speaking areas, although some schools in the big cities also teach it. The government subsidises Gaelic education. Gaelic only died where I live about 10 years ago so pupils still learn Gaelic, though their teachers are from elsewhere.
Some schools also provide Gaelic medium education for native speakers, where they can be taught in Gaelic throughout their experience at school, so even if they're learning Maths they can be speaking Gaelic. When I did my final exams I could have requested that they be Gaelic papers. That sort of thing is more common in the Western Isles were natives can still be found, though.
English has a lot of the same influences as German (such as Latin), and also directly trades some words with it. Gaelic is really from a wholly different family of languages.
It is also from a different sub-family to Welsh, a bit like how Spanish and Portuguese are in their own little sub family while French and the Norman languages belong to a different one. Or Russian and Ukrainian vs Czech and Slovak. Scottish Gaelic goes hand in hand with Irish and Manx while Welsh goes with Cornish and Breton. I can understand an Irish or Manx speaker to an extent, but I can't understand a word a Welsh person is saying beyond the little bits of Welsh I've managed to pick up. It's totally different, though we share the roots of words and basic grammar and the like.