as to your first point....
don't think you've thought this through.... let's say you're looking for advantage on a fight, you're hidden right click on the enemy, how does it do the attack you want. How do you attack objects out of combat and have the choice of which weapon? Are you always going to be walking up to a firebarrel and breaking it melee, or are you always going to beat down a door with ranged... That's why these buttons are here, so you have a choice without making the game decide the wrong option you can't get around.
Isn't the obvious solution here just to use the weapon that your character has currently equipped? If you have a melee weapon out, your character attacks with your melee weapon. If you have a ranged weapon out, your character fires it.
We already have a button to swap between weapon sets; no need to have redundant buttons to tell your character to attack with weapon set A or B.
