Minecraft – How to automatically set time to day with command blocks

If villagers are emitting hearts, then you've done all you could for them. Now it is only a matter of them entering love mode simultaneously, which is entirely in the hands of God of Random.

I've been frustrated with my villagers not mating once, too. You can't do anything, regrettably. Just ensure your villagers can meet easily once they want to and wait - possibly find yourself something to do nearby.

The answers you are looking for can be found on the Minecraft Wiki entries for scoreboard and commands.

Setting up teams

To assign a player to a team you have to set up the teams first, using

/scoreboard teams add <team> [display name]
/scoreboard teams option <team> color <value>

<team> is the name of the team, e.g. red or blue. [display name] is an optional longer name, used in the scoreboard display, e.g. Team Ocelot or Team Jacob. The second command sets the team color, use [tab] after color to see your options, e.g. red, blue.

The command to assign someone to a team is

/scoreboard teams join <team> [players]

I suggest using simple pressure plates at the cave entrances, with the command blocks right below. You can then use @p fpr [players] to select the nearest player, who is normally the one that triggered the plate. Alternatively, you can use @a[r=X] to assign everyone in an X block radius sphere around the command block at once, or specify a block range with the selectors x, y, z, dx, dy and dz.

Teleport by team

To teleport every player on a specific team, you can use the @a selector with the team specifier, i.e.

/tp @a[team=<team>] <x> <y> <z>