@nullius, @haltingprobability

Thank you guys for your posts, I find it much easier to learn about cryptography and comp science from examples and discussions rather than just raw theory, and this is exactly the kind of replies I wanted to see when I posted my question.

Now, I got more questions.

1. Would it be possible and would it make sense to add more digital signature algorithms and more hash functions with various key/hash sizes?

For example, shorter keys, signatures and hashes would result in addresses that have smaller transaction sizes, so people could optionally use them to save up on fees. Longer keys, signatures and hashes would provide some additional security for paranoid people, at costs of higher fees.

2. RIPEMD-160 is not the only hash function in Bitcoin's Script, there's also SHA256. Does this mean that even now we can create our own P2SH outputs with more bits of security than the standard addresses that useRIPEMD-160?

P.S. To clear any possible misunderstanding - I'm not scared of QC, my questions are purely theoretical and discussions like this are helping me to get a better understanding of Bitcoin in general.