Travelling from Lake Como to Venice Port

There is no town called Lake Como. Lake Como is a rather large lake and many towns are on its shore, including the city of Como, which gives it the name. Some towns have rail (Varenna, Como and Lecco do, for example), others do not (such as Bellagio), therefore it's important to know in which town you will really be.
If it's a town with rail, it will be easy to get a train from there and go to Venice. The journey will require one train change in Milan.
The porter service is available for Frecciarossa travelers at the major stations only. The Milan and Venice stations have porters and also luggage carts, however you will likely have to download the luggage from the Lake Como train onto the platform from where you (or a porter) will roll the luggage to the next train to Venice.
Smaller stations, like the one in Varenna, don't have porters and maybe not even luggage carts. So you will probably have to wheel the luggage to the platform and onto the train yourself.
I don't know if you travel with steamship trunks like the ones used in yesteryear, but extremely large luggage is a hassle for train travelers because in most cases you'll have to load it and download it on the train car yourself.
If you travel with reasonable amount of luggage (e.g. max one midsize suitcase each) the train is doable, cheap and easy. You need to be able to lift your luggage on board of the train. There are overhead racks at each seat and also a luggage compartment at the end of the cars for larger items that you don't want to bring to the seating area.
A private car will cost you dearly because the distance between Lake Como and VE is considerably long (up to about 3 hours, depending on your location on the lake). I haven't priced it but you can do so online with various companies. It will likely be around 400-500 euros. Another alternative is a car rental. Actually that would also be a nice way to visit the area and drive along the lake. Renting a large car or minivan for 4 will cost you about $80-100 day incl. no deductible insurance. Gas and tolls will need to be added. Tolls aren't that high however, maybe $20 to Venice.

macleaniris,

It's not difficult at all to take the train from Como to Venice. The shortest travel time appears to be 3H:23M, with one change at Milano Centrale. I'd probably use a departure from Como S. Giovanni at 11:17, arriving Venezia Santa Lucia at 14:40 (fares currently listed as low as €27.80 PP, reservations compulsory). I've never taken a cruise from there, so hopefully one of the others can provide information on how to get to the port from the station. You might find it helpful to have a look at the Mediterranean Cruise Ports Guidebook as I'm sure that will have all the information you need.

NO, there will likely not be any Porters to handle luggage (at least none that I've ever seen), so it would be a good idea to pack light. There are occasionally "helpful individuals" that will assist with that sort of thing, but they will of course have their hand out when they're finished. The change at Milano Centrale won't be difficult as it's just a matter of walking from one platform to the next (no tunnels or stairs). I'm 60+ and can manage a couple of Backpacks and a Camera bag, so you should be able to hoist your bags onto the train.

I've never hired a private driver, but for that distance I'm sure it would be VERY EXPENSIVE.

Happy travels!

Another tip for your arrival in Venice. As I'm sure you've read, Venice has two train stations ... Santa Lucia and Mestre. Unlike SL, Mestre is on the mainland, just over the causeway from Venice. Also unlike SL, you can get a taxi from Mestre to the cruise terminal. If you were staying in Venice I'd suggest SL, but since you're going directly to the ship I'd suggest you book your train ticket for Mestre because you can get a taxi (~25-30 euro) from the mestre station directly to the cruise terminal building. SL will require some walking with your luggage up and over a bunch of stairs, then navigating your way to the people mover tram. None of this is a big deal ... but why bother. Saving 30 euros (split four ways) is simply not worth the hassle of doing all this on foot. In my mind, Mestre and a taxi is a better option.

The only problem with Mestre is that unless the arriving train arrives at platform one the only way to get from the other platforms to the front of the station is via a very narrow tunnel and stairs down and up. I have looked all over Mestre but never found an elevator.

The problem is likely to wind up being the megasuitcases.

It is a shame you won't have time in Venice.

How are you getting to wherever you will be on Como?