Is there a observable void outside our universe that can give a clue on how far the next on is? How many universes can surround ours? What does a universes gravity well look like?
There is no way to know, if any other "different Universe" exists.
There is also a terminologic problem with it. Universe means, on latinic, something what "contains everything".
- If there is no way for the different "Universes" to interact, then how could we know that it exists?
- If there is a way to interact. For example, there is another spacetime where somehow we can pass through (or at least can see light or gravitation from it), then how could we call it as a "different Universe"? Then the Universe would be our current spacetime, and that other, together.
But the problem is a hypothetical one, as no alternate Universe were found until now.
We can play with different Universes in some theoretical constructions. For example, the spacetime of a rotating black hole looks like as if it would be some gateway to somewhere, out of our Minkowski-Universe (or to a different point of our current one). Google for Penrose-diagrams and for the topological extensions of the General Relativity, if you would like to play with it more.
Which direction is the next closest universe?
Which direction to the nearest unicorn?
How many universes can surround ours at a time?
We don't know the shape of our universe. Whether it's infinite or finite. Whether it's bound or unbound or whether it's part of a theoretical 4 dimensional multiverse or if 3 dimensions are some kind of natural limit. Without knowing how far our universe extends, or what (if anything) lies beyond it, it's impossible to answer. You may as well ask how many balls fit into a box, but you don't know the size of the balls or the box? See the problem?
Do universes redshift from each other?
In order to redshift, something needs to be both visible and have an established frequency, like the hydrogen signature of stars. Since we've never seen another universe, and we don't even know how to look for one, or if they exist, and without knowing what they're made of. Asking if they redshift can't be answered for many reasons.
There are alternative universe hypotheses out there, like the multiverse hypothesis and Neil deGrasse Tyson sometimes talks about other (theoretical) universes, but it's all very hand-wavy and there's nothing measurable and without measurement or detection, there's no direction, distance to or number of.
Maybe you should start with an easier one. Point in the direction of the 4th dimension. :-)