Spears and other types of weapons with an attack radius of 1 square or more are considered ranged weapons.
That is because they ARE, under the hood, Ranged weapons square-pegged into Melee ones.
This is most obvious when you use something unwieldy like a Hammer in close combat, get CQC-ed, and get deflected to a specific angle so that you can, in a blink it and miss it moment, see the "projectile" that came out of the Hammer flying away at the speed of light.
It's quite strange that bursts of shots count as one hit. It turns out that in order to remain invisible, it is better to use, for example, a minigun or multi-shot rocket launcher. While a pistol with a silencer is clearly not the best choice.
I'm under the impression that the Infiltration and Stealthy tags some weapons have are there for Deployment Restrictions purposes, i.e. can't sneak heavy ordinance and armor into cities and such, and have no other effect on Battlescape.
As for burst of shots as one hit, this level of abstraction I have no problem with (and which I visualize as "Enemy can only spot if they are able to transition from the GETTING SHOT AT PHASE to the REACTING PHASE)
Without that, auto-weapons would be penalized even if the enemy was killed in one burst (and logically the majority of autofire bursts would take between half-a-second to two seconds, so not enough time for spotting) and this allows shotgun blasts to count as one hit (otherwise: Oh no, I got killed by a shotgun, but the first pellet that hit me a nanosecond before the fatals ones was not fatal, so I spot the killer).
Not that there are no edge-cases that do not neatly fit, though.
