not much? i don’t have scale but 150g perhaps? i think that if you don’t need it waterproof then you can just extend wires, use them for support and get rid of case entirely. this would require sturdier shorting bar and some spacers probably but would be more compact
it’s 80cm long and can’t be folded, so if that’s portable enough for you, then yes
the point of this antenna is that it has something about 2-3dB gain over dipole, if you don’t need this a lots of smaller antennas with dipole gain exist
e: and also despite what its size could suggest it’s a single band antenna, this one is for 70cm but if you have space for 2m (2.3m long) then i think it still should be practical
that’s RG174, there’s only 25cm of it or so, so loss is probably not a huge concern (53dB/100m at 400MHz, so 0.13dB), and that common mode choke is probably a bit too much anyway