I'm sure that the Ottoman empire did help one of the south asian sultanates but only nominally. Whatever is the case Siam seems like a good commercial partner for Venice and a future protectorate in exchange for technology. You can work something out. Siam was one of the only nations IOTL (I could be very wrong in this) that accepted foreing trade and opened herself so easily.
Oman had a nicely shaped trade network, I don't think they would carve more land in Arabia, but... if offered some kind of deal, let's say 2/3 of Yemen they may catch it, and Venice will recieve Socotra as a naval base and some more(I don't know anything about the island apart from it's location so I cannot argue if it is worth it or not). Could the Andamans be a good option too?
Other thing that is easily possible is the republic purchasing back some of the islands they lost to the Ottomans or Montenegro. And Swahili looks nice for a colony even if it's a just a city: monopolic trade, the only ships that count in the trade of eastern africa (as in every other part of the world) are the most efficient. You just need a venetian town nearby to eliminate the local competition. As for Portugal... maybe later a colony in south africa is at the order of the day or in southern Madagascar.
Continuing with the trend a colony in america is not likely by any means, you will need a city at the gates of the mediterranean but that's simple. Purchase a strip of land form the Ottomans or Spain in exchange for some trade rights.
I don't think that the knights getting involved is a good idea, they sound as thay would cause more problems than solve them. Some religious fanatics going free around with swords in a multireligious territory that will not want you there, what could go wrong?... The only thing I see them doing is a very limited mercenary force for pretecting the pilgrims on their way to Jerusalem while the territory is pacified by the Ottomans.
Why would you need Rhodes when you have Cyprus?
*****Something I forgot to say in my past post: don't start the mediatization inmediatly, that can wait a century for the thirty years' war to start, get Venice involved for some cheap excuse and have a chance of invading the netherlands or stealing a city from the Hanseatic league. Farfetched, yes, very much so, but butterflies are flying...
Also, Da Vinci did desings for canals IOTL for river (I cannot remeber it's name now) to bypass Pisa and go through Florence, they were adapted and used in Milan, can they be adapted for the Po? It would looks really good for the river to go to Choggia instead of to the south. That would be a devastating blow to the other Italian cities: "Look at me, I can do whatever I want with the most important river in the peninsula and you can do nothing to stop me" And it also saves the trouble of crossing it during and invasion or defending it. Pushed away from the border makes it safer for a complente venetian monopoly of the traffic up and down the stream. Imagine the face of the lords of Ferrara when a Wargalleon bumps into their faces from the current!
The Àdexe is going in the wrong direction too, that means NOT to the lagoon.
The sediment will be a problem, however think about it as a solution when the city starts to grow outside of the lagoon. Artificial islands and terrains expansions were going on for centuries.
Ah yes, this is my current dilemma. Not the Coptic angle (should have that covered), but the rule over the Muslim majority. In the end it may be up to the Venetian power of persuasion to convince the Mamluk citizens of the city that they're better of being Venetian than ottoman... But I don't know if that carries much weight..
Cheap trips for Mecca and Medina bia red sea anyone? (Well, until the Ottomans control the city). I'm the only one thinking that the venetian future fleet in the red sea will open the gate for a complete turkish conquest of the peninsula?
I'm worried about the Ottomans having too much of an edge on the austrians. In a not so improbable future the Hapsburgs can fall into ruin. After all Austria WILL get gnowed down by the turks, the venetians and the prussians OTL and possible even more ITTL.
If Venice and the Ottomans gain control of the Red Sea, then the first thing they will do is search for a nearby base
That is surprisingly simple. There are many, many, many small islands surrounding the sea. My shots go for Shadwan, Sanafir, Farasan, Dahlac, Jazirat al Hanish al Kabir and Birim all of them protecting bottlenecks, and the four lasts ones can form a impenetrable blockade from the south of the whole sea. Mukawwar while on the other shore, is close to Mecca. Xaafuun, in the Somalian coast, while not an island is a prefect natural port, you can build a fort and close the itsmus in defence.
They have another shared interest with the venetians in pushing Spain out of Morocco. An outpost for the republic, more "oppressed" muslims under the banner of the moons.
On ther topic, is Rijeka/Fiume under venetian hands?