If you're using Shot as P/S, you're doing something wrong. Unless the skill "Requires a Ranged Weapon" or has "X% ranged weapon DPS", Ranged Weapon damage/speed/accuracy does not come in to play with the Skills actual damage. Ice Blade is not "Requires a Ranged Weapon" and so it has nothing to do with Bows. So, no, you really don't need to level your scout general skills.
Raising weapon proficiencies doesn't effect the magic accuracy at all. Magical Accuracy comes from Wisdom and some items have it as a ghost stat (Green stats included in the base item stats). You should be aiming for Wisdom to increase your healing potential.
Just as a rule of thumb, skills will say what kind of damage you'll be dealing after the damage number or percentage. The words after the damage number or percent is what the damage is based on.
Rising Tide, after it is modified by the elite skill, is treated as 2 seperate sources of damage as is stated in the description. It can miss on the physical part and hit on the magical part, it can critically hit on one and not the other or both but the physical critical hit rate on Ranged Weapon will decide if the physical part will be critical and Same for the Magical and Magical Crit Rate.