Do Throwing Weapons (by using a grenade) attacks require opposed 1/2 Fray tests to connect and damage enemies within the explosion area, like every other ranged attack?
Yes – but only for the initial throw:
For grenades the initial opposed ½ Fray test is to determine if the grenade hits the target, otherwise the grenade will scatter (p. 204).
When you are using a blast weapon, you may still catch your target in the blast radius even if you fail to hit them directly. Weapons such as grenades must go somewhere when they miss, and exactly where they land may be important to the outcome of a battle. To determine where a missed blast attack falls, the scatter rules are called into play.
To determine scatter, roll a d10 and note where the die “points” (using yourself as the reference point). This is the direction from the target that the missed blast lands. The die roll also determines how far away the blast lands, in meters. If the MoF on the attack is over 30, this distance is doubled. If the MoF exceeds 60, the distance is tripled. This point determines the epicenter of the blast; resolve the effects of damage against anyone caught within its sphere of effect as normal (see Blast Effect, p. 193).
Damage is therefore resolved for anyone in the area of effect without any further roll to hit (they're already hit – they're in the area of effect) unless there is cover in the way from the blast point (i.e. it scattered to the other side of a wall or something) in which case said object will provide armour points to soak the blast until it hits the character.
Grenades are nasty, but bear in mind some need an oxygen atmosphere in order to work, and if they miss there could be some very nasty consequences for hapless bystanders.
There is also the possibility of both…
Throwing Back Grenades (p. 200)
It is possible that a character may be able to reach a grenade before it detonates and throw it back (or away in a safe direction). The character must be within movement range of the grenade’s location, and must take a Complex Action to make a REF + COO + COO Test to catch the rolling, sliding grenade. If they succeed, they may throw the grenade off in a direction of their choice with the same.
… and Jumping On Grenades (p. 200)
Given the possibility of resleeving, a character may decide to take one for the team and throw themselves on a grenade, sacrificing themselves in order to protect others. The character must be within movement range of the grenade’s location, and must take a Complex Action to make a REF + COO + WIL Test to fall on the grenade and cover it with their morph. This means the character suffers an extra 1d10 damage when the grenade detonates. On the positive side, the grenade’s damage is reduced by the sacrificing character’s armor + 10 when its damage effects are applied to others within the blast radius.
(Page numbers are quoted for the PDF Second Printing One)