Congratulations - welcome to the next few years of walking around your home with a tape measure, scribbled "plans" on the back of envelopes and dreaming.

Live in your home for a year before you make any changes - different times of the year will show you were you have issues and where you don't, what works and what doesn't as well as how you use your home.

Once you start moving plumbing you're looking at a lot of money, your yard very possibly being torn up and then on top of all your costs if the plumbing pipes go through neighbours properties you're look at costs concerning them too. See if you can do what you want without moving waste and sewer lines.

When you've lived in your home a year, and have a look-book/ideas book then consult an architect to find a way to use your space more effectively and get it costed out - the cost just might be too much. Sometimes it's cheaper to sell and buy somewhere else long term - the financial, physical and emotional challenges of dealing with a major reno like you're talking about aren't to be undertaken lightly especially when kids, pets and alternate accommodation come into play.

What the others have suggested is good advice.

The layout isn't anywhere near great, depending on how you wish to use it of course.

There's a lot of areas that are circulation zones like the upper living area and the lounge near the entry. This makes it very tricky to lay out furniture in particular the upper living. The stair position is not good for the family area. The study has access from a bedroom, etc.. Good size spaces though, just the door positions and layout is poor. Shame as this could have been an incredible house if a bit more thought was put in by a good designer and an interior designer!

An internal reconfigure but keeping kitchen and bathroom in place will make a massive difference to this house. They're in quite reasonable positions already. It will be worth it once done as the size is quite generous and the void is something to keep as well, very spectacular for a townhouse to have this!

I would engage the services of a professional designer to assist, there is great potential here to have it become something very special.