Excellent.
Getting slightly ahead of the game I've just been looking at lift and tyre options
For your lift and such like, muddy mods is a ones top shop for lots of trick bits, lift kit, extended brake lines, chequer plate, engine tuning etc... And was set up by one of our guys,ie a LZ forum member, they started making bits for their own freelander and made it into a business.
Generally speaking highest you can go is a 2" lift kit, make sure you have camber bolts, and extended brake lines. As for tyres the biggest you can go to without spacers is a 29" tyre, 225/75/16 or 235/70/16 or there abouts. The limiting factor on tyresize is the tyres are precariously close to the spring seats on the macpherson struts at 29", for reference, the standard tyre is 26" diameter (215/70/16?), so lift kit and tyres will give you 3+1/2" lift. Coming from a fender you might think these mods are puny sounding, but you'll actually have more ground clearance under a 29" tyred 2" lifted freelander than you would under a stock defender. Be careful about which tyres you put on the freelander, because of their monocoque construction, really agressive tyres introduce a lot of noise into the cabin. Trust me, one of my hippos sets of wheels has kumho KL71's on them, while you do, or at least I did, get used to the noise, its still not pleasant. I've got BFG all terrains on the other set of wheels, and they are very pleasant on the road.
Engine wise, avoid the petrols. The choice is between either the older L series Diesel, or a TD4. If you want to tune it so silly numbers, you can do more to a L series, if you are wanting something modern, reliable and refined out the box with a bit of scope for tuning, TD4. If you plan on taking it off road, coming from a defender you'll miss the low box, crawling is achieved by slipping the clutch. However, the autobox is a hunny of a thing, beautifully smooth changes, virtually telepathic it just knows what gear you are going to need, and it gels with the freelanders transmission for offroading.
Our TD4 auto could run rings around our mildly fettled (boostpin, turbo turned up, decatted, egr delete, silicon hoses, tappets set up super sweet) 300tdi discovery in terms of acceleration. And the very rare time I had them both off road at the same time, I was surprised by how well the freelanders electronics and clever transmission worked on the terrain. The viscous coupling in the middle essentially acts like a limited slip center diff would in a "real landy". Couple that with traction control that brakes the spinning wheel(s) and thus transfers power to wheels with grip, as long as the ruts arent too deep for them, they will go seemingly anywhere. As an added bonus, they are 102" wheelbase, so longer wheelbase than a disco, and near as damnit on the holy grail 100", and they have naff all over hangs, so when lifting them even a smidgeon, like the 2" lift and 1+1/2" from the tyres, really makes a difference on what obstacles you can drive over as opposed to driving into it.
Back on point, if you are thinking of the freelander from the point of view of the dogs comfort, I'd suggest a 3 door, reason being they have the pop off targa roof panels that can be left ajar, and they have those silly pop out but not removable rear windows, I'd imagine if the dogs going to be in the car in summer, you could make them quite comfortable by having the tailgate window down, the quarterlights, and the sunroof panels open to create a through draft.