You’ve basically described classical Troy. 

Absolutely. And what’s even better is that we’ll get Dany’s Season 6 plot…but well-written. 

You’re in luck; I did some research into this a while back. Historically speakin, both medieval kingdoms and cities maintained navies for that very purpose. As to whether you’d consider them large, that’s tricky – wooden fleets have a relatively limited lifespan (14 years on avg, if I recall correctly), so fleet sizes tended to wax and wane rather dramatically as you’d have a big build-up and then that batch of ships would have to be decommissioned all at the same time. 

Now, “almost entirely safe from pirates” is a bit more complicated. The prevelance of piracy is driven by a number of factors: the relative power balance of different navies (if navies are weak in a given area because ships are needed elsewhere, it’s easier for pirates to operate), the extent to which political authority over a given body of water is fractured (i.e, the classic case of the Caribbean, where you had many different countries with competing colonies, which made policing difficult because pirates could cross jurisdictions easily; or modern-day Somalia, where the collapse of government authority on the mainland has given pirates a safe harbor to operate on), and the involvement of governments in piracy (in the case of the Spanish Main, when Spain and Portugal divided the New World between themselves, the English, Dutch, French, etc. went into the state sponsorship of piracy in a huge way, as well as claiming their own competing colonies). 

Geography and coordination also play a big role – it’s easier to deal with a contained body of water or a given choke-point, and it’s much harder to deal with wide open areas where pirates can simply keep running from you, as the Romans found out when they tried to suppress piracy in Mare Nostrum. At first the Romans tried to attack particular pirate strongholds – like the Antonine expedition against the Cretan pirates – but pirates adapted by just moving elsewhere in the Mediterranean, which led to a futile game of whack-a-mole. It wasn’t until Pompey’s extraordinary commission that the Romans attacked the program by dividing up the whole sea into districts and then making a concerted west-to-east push with their navy that swept the pirates in front of them and penned them in to ever-smaller areas until they were wiped out. 

I’m probably not the best person to ask about this (you might want to ask @goodqueenaly or @nobodysuspectsthebutterfly), but as far as I  know, we don’t know exactly how such a connection came to pass. 

All we know of the Tarth’s family tree is that “House Tarth of Evenfall Hall—an old family of Andal descent that boasts of ties to the Durrandons, the Baratheons, and more recently to House Targaryen.” One theory I’ve heard is that the Targaryen connection was one of Egg’s sisters who had an amour with Dunk and produced a child that was born legitimate, what we could call the Ossifer Plumm Theory, but it could have happened some other way. 

Well, that assumes Barristan lives to find out, but I think he’s “picked his prince” as Hillary Mantel would put it. 

Yes, and by conquering Pentos.