Can do, but Z is usually just a minor matching exercise. At those low frequencies it's not usually a problem. VHF tetrodes even make good high powered audio amp

Can do, but Z is usually just a minor matching exercise. At those low frequencies it's not usually a problem. VHF tetrodes even make good high powered audio amplifiers. I've even seen them used in ultrasonics (~50kHz) when older original tubes weren't available. Re second point, best options depend where you are geographically in the world, mix of services, etc. There's lots of different mixes/requirements.