Way to see who will win the election for Holy Roman Emperor in EU4

UPDATE: According to recent changelogs, the bugs regarding Legatus Natus and PrimasGermaniae are fixed in Patch 1.4

Here the old answer with an explanation of the bug:

I just checked the event files for both events (LegatusNatus.txt and PrimasGermaniae.txt).

They behave pretty much in the same way, so I will only write it up for LegatusNatus.

From what I can gather, Mainz gets the title automatically within one month:

# Legatus Natus
country_event = {
    ...    
    trigger = {
        papacy_active = yes                      <-- Pope must exist
        tag = MAI                                <-- This only happens to Mainz
        exists = yes                             <-- Mainz must exist
        is_elector = yes                         <-- Mainz must be an elector
        government = theocratic_government       <-- Mainz has to be a theocracy
        NOT = { has_country_flag = happened_763 }<-- The event has not happened yet
    }

    mean_time_to_happen = { months = 1 }

    immediate = { set_country_flag = happened_763 }

    option = {
        name = "EVTOPTA763"
        add_country_modifier = {
            name = "legatus_natus"
            duration = -1
        }
    }
}

And this is where things go wrong. For Mainz to get the title there is no need for a good papal relation, and Mainz starts out with a low one in fact.

However, the event for losing the title is as follows:

# Position as Legatus Natus Revoked
country_event = {
    ...
    trigger = {
        has_country_modifier = legatus_natus <-- Country must be legatus natus
        OR = {                               <-- and either of the following is true
            capital_scope = { is_part_of_hre = no } <-- not part of the HRE
            NOT = { government = theocratic_government } <-- not a theocracy
            NOT = { religion = catholic } <-- not catholic
            NOT = { has_opinion ={ who = PAP value = 100 } } <-- not 100 relations with the Papal States
            exists = no <-- Country not existing
        }
    }

    mean_time_to_happen = { months = 1 }

    option = {
        name = "EVTOPTA964"
        remove_country_modifier = legatus_natus
        set_global_flag = no_legatus_natus
    }
}

So within another month after getting the title Mainz will lose it again due to the Papal States not having an opinion of 100 of Mainz.

If that's no bug, I don't know what is.

I guess Mainz should either get good relations with the Papal States from the beginning or only get the title after they hit the 100 relations threshold.

Also the info text for losing the title is highly confusing. Nowhere does it say that you have to have good relations to the Papal States.

There is no auto explore button as there is with protecting trade etc.

However you can define multiple destinations by holding down the shift key whilst plotting your course. This allows you to select multiple ocean tiles. Therefore you can customise the course you wish a ship to take over the coming weeks/months by selecting lots of different destinations in one go.

The same applies with land units.

For Naval units there is also the Patrol option. Which once selected will cause the ships to repeat their orders in a loop. This can include docking at a friendly port for repairs.

A combination of using the Shift Key to stack orders and plot your desired course and then using the Patrol option to repeat those orders can be very handy and make Naval operations such as exploring a doddle rather than a chore.

I use this a lot when exploring, by making a ship sail up and down the same stretch of coast line over and over again. Then leaving him to it. You've just got to mindful of the ships attrition and make sure it visits port for repairs regularly enough.

Update - Limited to El Dorado DLC only

As @Max stated, you can now order fleets with explorers to automatically explore uncharted territories and coasts without taking attrition.

"Fleets with an explorer and at least 3 light or heavy ships (or a mix of both), that are in a port can undertake exploration missions such as exploring a sea, charting a coastline and circumnavigating the globe. When on an exploration mission, they do not suffer from attrition and cannot divert from their course."

See the Naval Exploration section of the EU4 wiki