How many times can you breed villagers?
Farmers will give any excess food they create to villagers, building their willingness to breed. At that point, all you need to do is place down beds, and your villagers will breed indefinitely.
Further, if you wait another 20ish minutes that little Villager will become an adult. As long as you restock the party room, you can use this to breed Villagers in Minecraft as often as you'd like.
The key for breeding villagers is to create enough beds for every villager plus one. Villagers generally won't breed unless there is an extra bed available for the child. Place the beds, including the extra one, near your villagers.
No, there is no such condition that a Villager has to be of the same type. It is possible to breed two Villagers who belongs to two different kinds of biome and even has different jobs.
Job sites are not required for villagers to breed. The breeding depends on the number of valid beds. If a villager is "willing" (see § Willingness below), villagers breed as long as there are unclaimed beds available within the limits of the village. All baby villagers are initially unemployed.
As Minecraft players know, these civilized mobs have a set routine and connect themselves to a bed so that they can sleep at night. Hence, if two Villagers are planning to breed, they must be able to detect three unclaimed beds around them with two blocks of space above each.
If a bed is destroyed and a new bed is placed on the same location without the villager realizing, the bed is no longer claimed, and can be claimed by a another villager. The result will be two villagers claiming the same bed. If a villager dies or forgets its bed, the bed will also become unclaimed.
If two villagers nearby are willing at the same time, they meet and spawn a baby villager in between them, like other passive mobs.
Zombie villagers that have been cured and are used to start a new village (player made) never breed, even if given more than enough food/beds. This does not affect naturally spawned/bred villagers.
As long as at least two villagers remain, the village will repopulate, very sloooooooowly.
Do 2 villagers need to be alone to breed?
You need to find villagers before you can start breeding them. Once you have found a village, and in turn found the two villagers you want to breed, you need to get them in a room alone together.
If the population cap is met, or the beds are obstructed, angry particles appear above their heads (along with the heart particles), preventing them from mating.

If a wandering trader comes by, they have a chance to get more villagers. The wandering trader will still despawn if he doesn't breed and convert into a villager, so the player will have to make them breed before he does.
The answer is a little complicated, as villagers need access to the sky to breed correctly. However, the community has found a way to work around this restriction without punching holes in their caves or underground villages roofs.
In nether wastes there are no villages.
Villager Breeders don't take that much space, but for the sake of this guide I will be doing this in a superflat. I recommend designating an area that is at least 10×10 blocks. This will become a village. The easiest way to create a villager breeder is to establish them in preexisting villages.
Nitwit has higher rate to summon Iron Golems when hurt by other mobs.
The final determining factor for trading prices is a player's reputation with a particular village. A positive reputation is gained by curing zombie villagers, though the zombie villager as an individual will offer a much better discount than the rest of the village out of gratitude.
They are exempt from despawn timers and, barring any bugs (looking at you, Bedrock Edition!), should not despawn on their own. They can, however, be annoyingly hard to keep alive until you get the hang of it. Villagers can die in all sorts of ways.
Leads can now be used on polar bears, ocelots, parrots, dolphins and old villagers.
Can only 1 villager move in per day?
Only one villager can be asked to move in per day via Island Tours at this stage. There are currently four ways villagers can move in: Invitations through mystery island tours. Villagers only appear on tours if you have an open plot unless you are in the prologue of the game.
However, villagers cannot breed constantly. There is a cooldown after two villagers breed that must elapse before they can breed again.
3) Cooldown after breeding
Once two villagers breed, they have a five-minute cooldown before they can breed again.
In 1.14+ there's no population cap as such. Simply, the two villagers breeding AND their baby must be able to pathfind to their beds (not necessarily reach them; pathfinding has its quirks like misinterpreting trapdoors).
If the population cap is met, or the beds are obstructed, angry particles appear above their heads (along with the heart particles), preventing them from mating.