Understanding Tabs

I have a question regarding tabs that I hope someone can help me with.

When two or more notes are stacked on top of each other( as in the example below) with strings between that do not have a note marked on them, how do you play it? If only the two particular notes are too be played should the string between
not be marked with an X at the beginning to indicate that it is not played. Or should all three strings be strummed?
And if only the two notes are played and not the open string between are they played simultaneously or one then the other? It sounds pretty basic but this has been confusing me for a while and I have been avoiding try to play songs where I see this.

----------------
----3--3---4----
----------------
----0--0---2----
----------------
----------------

When the numbers are posted in a vertical line like that, it means strum them like a chord. So what you have here is two chords, the first one repeated. I would strum the bottom four strings on this one and see if it sounds right. Let your ear be the final judge. Tabs aren't always accurate, so you may have to alter them a bit. If you were meant to pick the strings individually, the numbers should be off-set a little, and not in a line like that. Of course, the tab-writer may have screwed up.

DC

Chords?
That does not look like chords to me.
Here you're supposed to pick them both at the same time.
You can:
a) drop the pick and use your fingers.
b) hold the pick with the thumb and the index and pick the
lower note with that, and then pick the upper note with your ring finger.
If you're supposed to strum all the 3 strings, it would
most likely have been a X or something in the middle.

They are octaves, but thats errelevant.
I usually strum something like this by hitting all the strings, bt muting the uneccesary ones with one of my fretting fingers.

But if its an acoustic song, it may sound a bit strange
with the fretnoise you'll get from muting the string.

In cases like that, I'd probably fingerpick or use hybrid picking like how you said.

Ok, my bad. You're right, these notes should be finger-picked. If they were chords, there should be zeros on every string that should be strummed but not fretted, or X's if they are to be muted.

Your not wrong. I usually strum things, regardless if there is an X or not.