I don't think your 2nd suggestion would really stop the spammage.
The beams would still be very powerful, and if someone starts charging a Kamehameha while in a transformed state, the attack will still be very powerful. If he does it when nobody sees him do it, he can still fire the attack and get the kills.
Your suggestion works only under the assumption that all players are seen by all other players at all times, and thusly are able to interfere when someone's charging an attack, but that's simply not the case on most servers.
I don't know about your 1st suggestion though. See, when someone loses the oppertunity to attack with his charged weapon, it's his own fault for not defending, so losing his attack's charge is punishment for that.
If that person would retain his charge instead of having it auto-fire, as soon as that person recovers from any attack he suffered, he's able to quickly shoot the attack he already charged. That's not very fair, I think.