I'm due in July with my first, and we looked at budgeting a bit differently than you did, so I'll tell you about it, just in case it helps:
I'm in the US, so I'll be taking 3 months of FMLA. Approximately 1 month of that will be paid leave, the other 2 months will be unpaid. We've been saving for my maternity leave in a special account for a few years, and we'll have about 75% of my normal take-home pay amount saved for those two months of unpaid leave. That's probably way more than we need, as (like many of us on these boards), I save a great deal of my take-home pay. But hey, I (like you) feel better having a good cushion in place!
Prior to now, we've had about 3 months of living expenses in a liquid emergency fund, but I've been working towards doubling that ever since we learned that I was pregnant. I feel like 3 months is more than reasonable for a dual-income couple with no children (because why in the WORLD would we both lose our jobs at the same time???). But now that we have a little one joining our family, I'll feel more comfortable with having six months of an e-fund at the ready.
I believe the main expenses for a baby are the "equipment" things that you'll likely buy before he/she is here (like strollers, crib, carseat, etc). If you lived in the US, medical bills can be high, but since you're in Canada you're saved from that! Once they actually arrive, they're relatively cheap, particularly if you're breastfeeding and not going to pay for childcare! I'd think you're main expenses would be diapers if you choose not to cloth diaper, and any clothing/equipment you choose to pick up. Once the kiddo starts eating solids, they don't really eat all that much till their older, and you can choose to do things like DIY baby food if you're trying to keep things on the cheap. In other words, I think a realistic figure would be $50/month, but since you seem to be a conservative guy, factor $100/month to help feel "safe."
Overall, it sounds like you're making great decisions and are in a good place financially to have a kid!
To answer your cloth diaper question, my stash (which should last until the kid is potty trained) was around $450, but that's relatively high because of my own indecisiveness. Initially I wanted to only do the easiest thing, so I bought a whole bunch of new Bum Genius All-in-Ones for over $300, which should fit from 12 lbs-toddlerhood. I thought we'd just do disposable till the baby grew into the All-in-Ones. But then I started to feel guilty about the landfill issue for those first few weeks/months, so I decided I wanted to cloth diaper from the beginning. So THEN I bought a bunch of pre-folds and covers (costing ~$100) to use with the newborn. Prefolds/covers are one of the cheapest ways to cloth diaper. But now I wonder if I'll love the pre-folds so much that I'll end up regretting my expensive Bum Genius purchase. ALL of my cloth diaper stuff has been bought new, so you can certainly cloth diaper for less than what I've paid. However, Bum Genius typically retail new for $20 each, and I got mine for <$15 each, so while I could have bought used for a bit less, I felt that the difference in costs between used and new-on-sale was not enough for me to want to buy used. If I could do it over again, I'd just spend the money on the prefolds and covers to try it out, and then decide from their what to do as the child got larger. It seems quite silly that I'm doing the more difficult type of diapering first when it's a newborn and I'm a new mom, but I wasn't willing to fork over the cash for all-in-ones for a newborn (they're too expensive to justify the cost with the short amount of time that they'll wear them, AND it seems that getting all-in-ones to fit right on a newborn is somewhat challenging as well, so prefolds seem to be a good choice for newborns). There is SO much information online about cloth diapering if you need more info - all of the retailers (Cotton Babies, Green Mountain, Diaper Junction) have info on their sites, plus there are blogs and youtube for more info.