Returning at your questions, relevant Mr Nekoogar,
Here are my answers
1. Does string theory predict the Multiverse?
probably that strings indeed can converge for these multiverse, for the quantumgravitation also and my humble theory of spherisation with 3D soheres.
2. Can the Multiverse theory be tested using CMB?
there ,it is very important because indeed we can analyse with the microwaves and the standard model and our lectromagnetism but we must consider this matter not baryonic.It is a different analyse.We must better understand our universe in better understanding these BHs and dark matter.If the multiverses exist and that we have many sphères ,so we can utilise the same logic of reasoning also for these others constants probably like G, c ,h,the cosmol constant....
3. Are we looking for any signatures of a past collision between our universe and another bubble universe?
Intriguing these universal sphères in collision, like all,like if all was dedicated to be in unification around the main primordial cosmological singularity....What is this central BH, in our universe or like mr tegmark says in the multispheres withalso a center??? wowwww
4. Why was entropy so low at the Big Bang?
perhaps this cold still and always....has more than we can imagine to explain us.
5. What is the relationship between cosmological constant/Dark energy and the Multiverse?
It is not easy,but perhaps that simply the dark energy is an anti gravitational push permitting to balance in the future the expansion,spherical.The others universes in logic act like that also but with different constants.The cosmological constant and the general relativity can be harmonised in considering the matter not baryonic still,this dark matter.The gravitational light seems an evidence.The stars are just like trasformators simply permitting to build matters.Photons are like a coded fuel.The cosmological constan,t and this dark matter permit to balance the exapnsion and the increasing mass, we shall have in logic a maximum volume and after a contyraction towards the equilibrium, the min vol in logic.The others universes have their intrinsic dynamic of evolution, the time also became intriguing, have we the same age ?? already that we know only our electromagnetic age if I can say, not our gravitational age, you imagine ???
6. Does Loop Quantum Gravity predict a Multiverse?
probvably that maths still can converge if the postulates and axioms are well choosen and respected.All Tools are welcome in fact
7. What is the relationship between magnetic Monopoles and the Multiverse?
8. Are there any differences between inflation theory and string theory in predicting the Multiverse?
I have never thought about this, I don't know.
9. What is the relationship between the geometry of space-time and the Multiverse?
The SPHERE of course and the sphères they turn so they are ,....:)