Ragna aims his crossbow at the hunter, but doesn't shoot yet. If he makes a hostile move, he will shoot. (Ready action)

"the man aims his gun at Bills head" 'If you shoot at this distance you'll kill all of us and blow up the door punk' "he smirks at the two"
Johnny runs out from cover and attempts to knock the man down with a sweep kick
Lone Hunter: Takes 2 damage and is knocked down

In that case, since the lone hunter is knocked down, Ragna will draw his mace. Because the unknown person seems to be helping us, Ragna will flank the lone hunter and smack him unconscious. (The lone hunter is not in a good position to shoot, since he is in close range with Johnny and would provoke an attack of opportunity if the hunter shoots, I think.)

"I don't think this mace will blow us all. But it might to you."

"The hunter groans loudly as consciousness leaves him"
Lone hunter: Takes 4 damage and is knocked out
Johnny sighs loudly and looks at the pair of them 'hate to give orders when we haven't introduced ourselves but we should get inside, there is alot of blood around here and I just hear some very messy affairs going on in the jungle'

"Yea. We had a 4 meter large cat on us. The ruins will be much safer."

Ragna goes inside the ruins, with his crossbow.

(he's right in front of me...that would have been nice to know)
Bill, on this note, also steps inside, making a note to watch out for this guy on the way out.

Johnny shakes his head and yells at them 'you two amateurs or what? Ruins like these always have one obvious door, a trap or just a wall of stone, and one hidden door.' He nodded toward the unconscious man.
"Near the hunters right hand was a patch of grass that seemed out of place to the rest"

Ragna will check out the grass that seems out of place.

(I did see some ruins that had no doors in some games. It can happen. Although, even Skyrim's ruins have doors)

(Even then though, some ruins have an inaccessible door at the front, and a secret door in a cave or in the floor)

(Hmm, if the patch of grass is hiding the mechanism to open the door, how do you get out of there once someone locks it from outside? Anyways, we don't know what it is until we know the results.)

(of course, we need a ten foot pole, stat)

"I suggest we go out into the woods to find a very long stick, and poke it from a few feet away, considering, you know, it might explode or something."

(Well, when he checks the patch of grass, he doesn't touch it at first. In fact, he tries to see what it is, not too close from it. Because he doesn't want to step on a mine, but he doesn't want to do actions that would waste time either.)

Johnny shook his head 'explosives in these sorts of places aren't that different from our own explosives, we'd be better off disarming it than risking blowing up an entrance or something, assuming it is explosive at all'
"Ragnas inspection of the grass reveals nothing malign about it at this time, but he will need to inspect it closer"

He will inspect a bit closer, trying not to set off the explosive if it's one.

(This is the time where the skills like disable device comes to use. Knowing how some traps work allows you to avoid setting off traps. Also, a 10-foot stick won't keep you safe from an explosive if it's one.)

"Even still, such an object will be useful for checking for booby traps inside, which I have no doubt there will be."
Bill steps back from the entrance, and lets Ragna get to work.

"Of course, I could probably just blow us a new entrance, if this one collapses, I am a professional demolishions expert, after all."

Johnny shook his head again 'that'd cause more problems than it would solve'
"Upon closer inspection the grass appears to conceal a hatch"

Ragna will have a quick look to see if there are traps. If not, he will check how this device work.

"Ragna does not find any traps"

So I try to check out how the hatch works, then test it. (I'm assuming this device is connected to the door.)

"the hatch opens revealing a ladder" (It IS the door)
'Well whaddaya know?" Johnny approached the ladder and dropped a coin down the hole

(Does it seem dark down there, or is there a bit of light?)

(bright enough to see, but you certainly don't need sunglasses)

Bill makes sure noone is following them, watching the forest, bazooka at the ready, and waits for the other two to get inside.
"I'll watch the entrance till you get in, then I'll go down after you, and shut the hatch. Can't have anyone following us, and I DO have the heavy firepower...unless this guy here *he points at Johnny* is packing something I'm not aware of."

Since I'm the team's ninja-mage, I'll quick check the ladder. (You never know, the ladder might have a trap on it. I've seen a ladder with electricity before.)

If no traps, I'll go down the ladder to make sure no one steps on a trap by checking for traps and disabling them. I also try to make the least noise possible. (Did the coin activate anything?)

Johnny shrugs 'maybe I am, maybe I ain't'
"The coin hits with a clink at the bottom of the ladder"