I have been playing solely Venice as I love the constant anticipation and diplomatic challenge that comes with a) being non-HRE bordering the usual Emperor, b) competing with the 2 muslim powers for trade, c) holding the other italian powers in check, d) racing the other major powers (France, Spain, Portugal) to stay relevant. I have become pretty good at it, and I usually quit games because I am far too powerful. I would like to add some advice to your guide.
1) The main strength of Venice is that it is FLEXIBLE. You have the ability to expand into the rich Italian provinces with your strong army (and mercenaries), or into Austria during other wars. You can expand into the Balkans or snipe Greece from the Ottomans for Alexandria -> Ragusa -> Venice trade, which keeps the Ottomans poorer. You can use your merchants to influence the flow of gold around the Mediterranean, influencing the Genoa traders by never letting the money arrive. You can expand into Egypt to head toward India for trade. You can snipe Constantinople from the Ottomans and slowly outpace them. The only thing you can't really do is colonize the New World, but you can do that if you focus on it. Simply ask for fleet basing rights from Portugal and explore Brazil.
2) The main weakness of Venice is that she has strong enemies everywhere, and the more you expand/trade, the more people you'll piss off. You can't afford to fight more than 1 major power at once for awhile, and even that should require money for mercenaries.
Ok, some specific advice.
3) Watch your AE. You can't afford to let coalitions form against you like they did historically, as those coalitions may involve HRE Austria, France, Ottomans, and the Mamelukes, SIMULTANEOUSLY. That's scary!
4) Convert early if at all, and grab Rome if you do. And maybe Judea. I have tried staying Catholic and I have also tried converting to both Protestant and Reformed. I definitely feel that Protestant is the way to go as Venice. First, you should take Papal State territory early in the game as it is rich and does not involve Austria. Since you have: pissed off the Pope, all the other majors will remain Catholic (they have too much Curia control), and holding Rome as non-Catholic is worth Prestige and a Missionary, I strongly recommend converting. I find the -10% Idea Cost to be much better than +1 Adviser options. Money is money, you will have plenty anyway. Convert early to get lots of free conversions. In my current game, I am 100% Protestant, did NOT take Religious ideas, and have a lot of land in Italy, the Balkans, Greece & Islands, and Egypt/Syria. It was easy and painless because I swapped early.
5) Snipe Constantinople IMMEDIATELY, as well as grab Ragusa. The Ottomans will not know quite what to do once you acquire Constantinople, and that is a ton of money you get and they never see. I also snipe the rest of Greece, Diploannex my vassals, wait for the mission to take Cyprus, and then use that to take Rhodes. And use Cyprus to take Egypt piece by piece.
6) I recommend using Plutocracy, as you don't need the Military points for actual Military, and Plutocracy improves your economy with Mil points! And the finisher is gorgeous.
7) You do NOT need Diplomacy or Religious ideas. Take something in the Diplomatic area for your second branch (so you can spend Adm on cores and tech for more idea groups), I don't think you need Trade so early. Perhaps Naval to compete with the Ottos if they take it too. You'll need that morale boost, and the forcelimits help you trade!
8) Punish Austria and Ottos frequently. Whenever Austria is in a war, make sure you have a claim on one of their provinces (Gorz first), and then try to take some rich Italian minor. Get both provinces in one war, weakening the Austrians and killing 2 birds with one stone. When the Ottos get in an Eastern war, or the Mamelukes get into war with the Ottos, jump them. Block the Bosphorus against Ottos, destroy Mameluke armies when taking Egypt.
9) Don't form Italy unless you really need to reset your AE. Venice's ideas are better, and Venice is a better trade node (less sharing with France and Spain) to collect in. The other reason to form Italy is if you colonized, as the only way to get New World trade over to you is at Genoa. The route is Brazil -> Ivory Coast -> Timbuktu -> Tunis -> Genoa.
People are asking about ships, ideas, and culture. If you form Italy, you will NOT lose Plutocracy, but you will be able to also take Autocracy. You can always lose accepted cultures if the total tax income from that culture falls below a threshold. The exception is if you formed a culture-union country (like Italy), then your culture group is permanently accepted. Finally, I recommend always keeping a galley fleet + transports that is 1.5 times the size of your enemy's fleet. Split your light ships to the trade nodes so you have somewhere between 50% and 70% trade power in the node. Less % is more efficient, and above 70% is atrociously inefficient.
Have not done the Constantinople thing early. 
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