Corrosion and galvanic corrosion (Basic level)

[Juanda]

TL;DR Summary

I'm trying to understand galvanic corrosion, the rate at which it'd happen given some conditions, and some practical means to reduce its impact. For that, I first need a deeper understanding of normal corrosion too.

Let's start with something simple. Imagine we have a block of pure iron on an electrically insulated table (maybe plastic). It's exposed to the normal atmosphere you'd find in a city several kilometers away from the sea.
According to this link, this would be the reaction.

Rust is a combination of several different oxides of iron. The equations below show the steps involved in one of the many processes of rust formation.
$$\begin{align*} 2 \ce{Fe} \left( s \right) + \ce{O_2} \left( g \right) + 4 \ce{H^+} \left( aq \right) &\rightarrow 2 \ce{Fe^{2+}} \left( aq \right) + 2 \ce{H_2O} \left( l \right) \\ 4 \ce{Fe^{2+}} \left( aq \right) + \ce{O_2} \left( g \right) + 6 \ce{H_2O} \left( l \right) &\rightarrow 2 \ce{Fe_2O_3} \cdot \ce{H_2O} \left( s \right) + 8 \ce{H^+} \left( aq \right) \end{align*}\nonumber$$
Iron is first oxidized to iron (II) ions by oxygen. In the second step, the iron (II) ions are further oxidized and combine with water and oxygen gas to produce a hydrated form of iron (III) oxide known as rust. Rusting is one of many examples of corrosion. Corrosion is the deterioration of metals by redox processes. Corrosion causes enormous amounts of damage to buildings, bridges, ships, cars, and other objects. It has been estimated that corrosion costs the U.S. economy over $100 billion each year. A great amount of time and effort is spent to try to limit or prevent corrosion.

I have some questions about that chemical formula regarding "normal" corrosion.

1. Are there hydrogen ions floating in an aqueous solution in the atmosphere? It seems it's a requirement for the oxidation process to happen but I find that strange since I don't know how it can be in an aqueous solution in gas and because ions tend to neutralize at the first given chance because the electric forces are very strong (compared to gravity for example) so I don't see how it can last long enough hanging there until the chance to react comes its way.
2. How would the proximity to the coast magnify or accelerate the chemical reaction? I assume it must be related to the greater humidity and the possible presence of $NaCl$ which might combine with $H$ or something like that but I can't find the chemical reaction put in terms like what's shown above.

Then, for galvanic corrosion.

Imagine now there is a block of copper on top of the block of iron. First, visualize it in the same scenario far away from the coast. We have two dissimilar metals in contact and the atmosphere will be the electrolyte.
Can you provide what would be the chemical reaction in such a scenario? When I checked iron-copper galvanic cells, it seemed the conditions were more strict than just standing there in electrical contact and exposed to the atmosphere. I mean, if there is no copper available in the atmosphere, how can the galvanic reaction occur?

Lastly, how would the process be accelerated if the experiment were repeated near the coast?

Later I'd like to propose a few more scenarios with different materials but I think this is a proper starting point to get a grasp on the topic.

Thanks in advance