Quantum entanglement means that multiple particles are linked together in a way such that the measurement of one particle's quantum state determines the possible quantum states of the other particles. But my question is that if we randomly pick up any pair of particles from anywhere, will it be entangled? Does it mean that all particles in the universe are entangled to each other? For example- I pick up an electron on earth and an electron which is 1000 million light years away from the electron on earth, will both of those electrons be entangled? Also does this entanglement work only with similar particles, can two different type of particles like an electron and proton be entangled? (Extra question: does quantum entanglement work with only spin of a particle?)
To answer your questions one by one:
No. All the particles are not entangled. If they were so, we'd have quantum computers by now. Entanglement is a phenomena very sensitive to environment and even the slightest interference from outside can diminish the entanglement between two particles.
Different type of particles can be entangled. In a pair production the produced electron-positron are entangled.
Again No. Any quantum mechanical property of the system can be entangled. Not only spin but position ,momenta, total angular momenta etc.