Quote from: butka on April 07, 2018, 12:17:03 PM

2. What are the advantages (or disadvantages) of the newest generation of SHA3 Keccak hashing function vs SHA2-256?

One disadvantage would probably the high performance on ASIC's [1] which would lead to a more centralized system.
There is no need to switch to SHA-3.

Statement from NIST:

Quote

Currently there is no need to transition applications from SHA-2 to SHA-3

Source: https://csrc.nist.gov/projects/hash-functions/nist-policy-on-hash-functions

[1] https://ehash.iaik.tugraz.at/wiki/SHA-3_Hardware_Implementations#High-Speed_Implementations_.28ASIC.29

Quote from: butka on April 07, 2018, 12:17:03 PM

3. Is the only benefit of hashing transactions their compact representation?

No. Hash functions are also used for verification.
Probably the simpliest example: Checksums [2] (e.g. Message Authentication Code (MAC)).

In Bitcoin a hashing function allows to easily verify all transactions within a block.

And additionally it serves as PoW.

[2] https://en.wikipedia.org/wiki/Checksum