Yes, ranged attacks from spells are typically considered to be "weapon-like". This is definitely true of rays (and almost all ranged touch attack spells are rays) since from the rules:

You aim a ray as if using a ranged weapon

The rules further clarify that rays function as weapons for several other purposes, and the FAQ makes this very explicit:

Do rays count as weapons for the purpose of spells and effects that affect weapons?

Yes [...] rays are treated as weapons, whether they're from spells, a monster ability, a class ability, or some other source

The same rule applies to weapon-like spells such as flame blade, mage's sword, and spiritual weapon--effects that affect weapons work on these spells.

Most ranged touch attacks which aren't rays are things like acid splash -- spells where you actually throw or aim a physical object. Those are even more "weapon-like" than rays, so it's probably simplest to say all ranged touch attacks work like this.

There's another FAQ that indicates you can take "Weapon Focus (ray)" and the like; strictly speaking I guess those wouldn't apply to orb spells like acid splash.

This is all following the precedent set by 3.5; in Complete Arcane it specifies that rays and touch attack spells are "weapon-like" and thus interact with feats in the same way that other weapons do, with a split between ranged/melee type spells.

Reading the rules in a strictly literal sense, I don't think it actually counts anything as a true grapple.

1. Make a ranged attack against a foe that has something you can pin (clothes, armour, bags) and something to pin it to (nearby perpendicular surface).
2. If you hit, you roll an opposed grapple check. Yes, while this uses the rules from grappling, it does not specify anywhere that you or the target are considered to be in a grapple.
3. There is no required opposed grapple roll for the opponent to escape, they simply DC15 Strength or Escape to break free.

I think the only reason you make a 'grapple' check at all is to include all relevant size/skill factors. A Huge creature's arrows would basically be the size of a javelin to a small creature, so it stands to reason that bigger projectiles pin more successfully than smaller projectiles.

It doesn't specify that you or your opponent are considered to be in a grapple, nor does it specify that normal grapple damage applies (or constrict damage for that matter). It simply requires you to make a roll that uses all relevant bonuses for grappling in terms of size and strength.