The Rift

You can easily access the shelf above without a need for ropes or a skill check.

Not magical. Good call

The stones are about 30ft by 30ft square though they have been somewhat eroded you see they are made of granite and cut with precision. The path is two columns of stones like a two column grid, with the stones spaced about an inch from each other. This path goes off into the distance beyond your vision.

The sea floor is sandy and in some places it is so soft, you can sink down into it, depth varies from up to your thighs to even deeper. There are small bottom feeders here that scurry off at your approach. Around you it is very uniform and seems like a very large plain of sand with only the occasional seaweed.

Opposite the stone path, at the edge of your dark vision are two black pillars spaced apart much like road markers though you estimate them to be about 15ft high each. There is a lack of detail at this distance in the slightly murky water.

A WIS check will deter.ine if you recognize the shadowy figures. Unless you have some language or Arceology background, you will not be able to decipher the cuneiform.

There are no skills listed, but I don't feel that a surprise roll will be relevant. I HOUSE RULE that attribute checks are 1d20 vs. Attribute. Roll lower that or equal to the attribute for a success.

Bam! Successful WIS check. You recognize the shadowy figures as 3 rays, most likely more of those intelligent ones.

Yes they are 70 yards away.

outdoor ranges are in yards.

Anything closer than 30 yards will require some stealth. How close will you get?

Yessir! Divide feet by three

Surprise
If surprise is a possibility, roll 1d6 for either or both groups, as appropriate. (Roll only once for each side, not for each individual character or monster.) If the result is a 1 or a 2, the group is surprised. If one side is surprised, the other side automatically gets to take actions before the first initiative roll.
A party that includes a Monk or Ranger, however, is surprised only on a roll of 1.
It is possible for both groups to be surprised, effectively canceling out the effect on both sides.
And here is something really nasty: If a group is surprised, each person (or creature) in it has a 1-in-4 chance to drop one or more handheld items!

Initiative
Each side rolls a d6 and the side with the highest result is the winner. One roll is made for each side, not for each individual. If this is the first round and one group was surprised, the other side gets to go first automatically, without having to roll a die.
At the beginning of a combat round, each side rolls a d6 for "initiative" — the opportunity to act first. The side with the highest roll wins, and that group acts first.

Movement and Missiles
It is up to the Referee whether missile fire includes both shots from a weapon with a rate-of-fire higher than one; a longbow, for example, shoots twice in one round.
In many games, only the first shot is allowed in this phase, with the second shot being fired after melee and spells are resolved.

In this game you may fire your full Rate of Fire on your turn.

Well, I wasn't going to roll for surprise as you can see them but they haven't spotted you. You have the advantage of surprise in this case and get an automatic surprise round.

Does Mole put on his weighted belt or will he continue to swim?