Your brain and your hands have "positive transfer." That is, they will automatically carry over much of Canon's movements and skillset to your new camera. It's not 100% but you'll be surprised at the ease which you'll learn. Put your money in the body. Build up lenses over time. Buy a walkaround first and enjoy, enjoy, enjoy.
Buy a very good used tripod. Test the bejeesus out of it or splurge and by new. You will never regret it.
After trying a third party grip on my Canon 5D MKIII, I bit the bullet and bought the real thing. The Z----- kept loosening up and occaisionally did not seat properly even when tight. (I don't like to overtighten). I do use only Canon batteries and sometimes, they weren't held snugly. A little fooling with the cover usually did the trick, but I don't like to have to fool around with anything while I'm shooting. The Canon grip is perfect.
Congratulations! You seem to have caught Nikon on the cusp of their reversal of their traditional customer service policy. Enjoy your 610.
Eventually, you'll break away from working around a lens and start working around the body and lens combo. In that situation, of the two you mentioned, the Canon 5D MKIII is a far more versatile pairing. They really become the proverbial apple and orange, or apple and grocery store. The Canon is as close to a mid-price super camera as you can find.
The best I've tried is Lightroom. Especially when it comes to organizing for publication.
Cuda cores is the dfinitive measure of performance. Your research should include a comparason of cards by this measure. Note the extreme variability in price.
http://www.videocardbenchmark.net/high_end_gpus.html
I have a Canon 5D MKIII with very high ISO options. Its internal software does a great job od reducing graininess. You will also find this feature available in other "high end" DSLR's. Check out dpreview's testing prior to buying. I find they do a pretty thorough job of covering high ISO as it's a hot topic.
For Architecture, the wide angle would help best. You'll find yourself in close quarters most of the time. That being said, Italy has some great opportunities for some long-view shots, too. I agree that both lenses would be worth carrying. You really don't need to bring as many clothes as you think. Or kids.
Calling customer support is the definitive way to sign out. They'll give you an actual date that your software is no longer effective.
If RAW files are being stored, I'd recommend calling Apple support first. They have some great equipment with high-speed transfer rates (though you pay for it). They'll help you purchase the right unit(s). Their user's guides and the LR guides will get you organized. My son is a graphics designer with tons of Apple equipment. He stores "by the book." No shareware. And since his income depends on it, it seems to have woeked for him.
I, too, have a Canon 5D MarkIII and use the 24-105 as a walkaround and photojournalistic lens. It's very smooth and produces great shots at both ends of focal lengths.
Deal only with the manufacturer's Customer's Support. Then, get the latest firmware from your external hardrive manufacturer and install it. Second, get the manual. You should be able to see your folders (if you put your photos in folders originally) or individual photos arranged by whatever default system your hardrive uses. If recommended by the manufacturer, you can use other software to look into your external hardrive, too. External hard drives have changed dramatically in the last several years from simple boxed drives to veritable, multiplexed independent storage systems. Enjoy retrieving the memories!
Why not just go somewhere that looks like Russia? There's parts of the the Bronx like that.
Buying a camera for its looks?