In terms of cubic footage, they are pretty similar. In terms of ease of use of that space -- you might prefer having everything up close, especially if you tend to find science experiments in the back of your fridge. If not, you might rather have the added space in your kitchen for another use. Just depends on your needs and preferences.

You don't know what family life is like. No one can tell you. What we can tell you is that what you think your lifestyle is will change in ways that you can't anticipate when your child is born. Additionally, remodelling is very stressful. It's really not a great thing to undertake with a hard deadline, and you don't want to have no kitchen when the baby arrives. If you have a lot of time, and a good, full service firm handling all of your details, and they expect to be finished several months before the baby, then go for it. Otherwise, have a really serious talk with your wife and make sure that she's comfortable with this whole redo right now. It concerns me that it's you, not she, asking the questions. If that's your way of doing division of labor, fine, but if this is your project, not hers, please, please talk to her some more and make sure she really really really wants to do it. The baby is enough of a stressor without a kitchen remodel. I wouldn't go too far off of what is standard in your neighborhood if you really think you'll be moving within five years. Toronto is very different from where I live (SoCal), so I won't speculate on the expectations there, but where I live, a 36" fridge is expected by buyers (bigger if sxs), but built-in trumps freestanding. In a small apartment, smaller is fine, but in a 2000 sf home, not so much. If what's there now is dreadful, and they can just plunk in a wonderful Leicht kitchen will be quick and easy (doubtful), and you don't care what you have to spend to get there, that's fine. If it's workable as is, and you really expect to move in five years, it's not really worth remodelling at a time when so much else in your lives is changing. From a purely design/aesthetics point of view, since you asked, either size fridge is fine. Built-in is always going to be less obtrusive than free standing. You really don't know what your needs will be when you have a baby, however, and you may be unnecessarily limiting yourself.

I like the second plan much better, with some adjustments. I love that you've moved the mudroom door, and I realize that you're replacing a window with a door, so that spot is pretty much set. However, your range should really move away from that door so that you're not constantly being interrupted by people using that door. It's also not really safe to have the range so close to the door, just in case you have a pot handle sticking out for some reason. I'd move the range over a bit more to the right, or even to where the d/w is in the 2nd drawing. I'd rather fight the dishwasher door than the stove, but that's my personal preference. I see that you've changed the cabinets above the sink to open shelving in plan 2. Is there a specific reason for that? I think I'd prefer cabinets there, possibly shallower than the other uppers, but I'd rather have cabinets to the ceiling since your kitchen is so small. As to the fridge area, that looks pretty good except I think you may be missing an opportunity to get more storage by not putting anything in front of the HVAC bump-out. Even if you put in shallow uppers to the ceiling and installed some sort of rolling cabinet base there, you'd gain a ton of space. I don't think you could do a permanent island, since 63" doesn't give room for aisles on both sides, but you could do something that rolls out when needed and parks against the wall when not needed. If an island isn't helpful/important to you, then a run of cabinets in that area would be nice, IMO. WIth that, you could still have your open shelving, or you could create the area next to the fridge as a sort of hutch for the kitchen.

We will have the 27" subzeros (all fridge and all freezers). I think the benefit to counterdepth is that stuff doesn't get lost in the back of the fridge! Most of the space in my current regular fridge is used up by stuff that probably shouldn't even be there anymore. The shorter depth may impact your ability to store larger platters during entertaining, which is my biggest worry. I'm likely going to get a fridge for the basement to store the big stuff for parties.