2. If you solder the plate of the two tubes together and at the same time solder the cathodes together, one tube can hog the bias current. By having seperate bias set resistors in either the plate or cathode, this hogging is reduced to where we don't care about it.
Slight differences in AC operation aren't that big of a deal in most cases.
Play safe and play longer! Don't be an "OUCH!" casualty.
Unplug it, discharge it and measure it (twice) before you touch it.
. . .Oh!. . .Remember: Modifying things voids their warranty.