1) As per Sayyid Sistani's rulings, are there certain instruments I am not aloud to learn to play, even if I use them only to practice non-amusement gathering styles of music? More specifically the piano, acoustic guitar, or violin?

2) Do his rulings show we should generally stay away from learning to play music (even if it may be considered a halal form) i.e. is there unavoidable spiritual risk in the act? I ask because I've never read a positive hadith regarding music, so the "ONLY amusement gathering music is haram" rulings seems quite liberal.

542. It is permissible for adults as well as children to learn the art of halal music in music schools or other places as long as their visits to such places do not have any negative effect on their proper upbringing.

https://www.al-islam.org/a-code-of-practice-for-muslims-in-the-west-ayatullah-sistani/music-singing-dancing

567. Question: Musical instruments are of different kinds. Sometimes they are used in musical gatherings and sometimes for soothing the soul. Is it then permissible to buy these instruments, manufacture them, deal in them, or play them to soothe the soul or listen to the ir sounds when someone else is playing them?

Answer: It is not permissible to deal in the instruments of haram entertainment: neither selling nor buying, just as it is not permissible to manufacture them and accept remuneration for making them.

“An instrument of haram entertainment” means that its physical shape—that gives its value and eventually the purpose for acquiring it— is not suitable except for use in haram entertainment.

1) As per Sayyid Sistani's rulings, are there certain instruments I am not aloud to learn to play, even if I use them only to practice non-amusement gathering styles of music? More specifically the piano, acoustic guitar, or violin?
2) Do his rulings show we should generally stay away from learning to play music (even if it may be considered a halal form) i.e. is there unavoidable spiritual risk in the act? I ask because I've never heard of a positive hadith regarding music, so the "ONLY amusement gathering music is haram" rulings seems quite liberal.

1- No. If you are not going to use them to produce music suitable for harām entertainment, then, you can learn.
2- No. It depends on the type of gathering.