Depends how much clay is in the dirt. Some clay is ok, since it may help retain moisture - but too much is def. not fun. If it's very clay'ish, I'd add sand and as much compost as possible. And if you haven't planned for a compost pile yet, you may want to. Make sure it's away from doorways/windows as they can smell when things go wrong, and they can also attract a lot of bugs. I'm not sure who you could get in your area to do the soil test, I'd probably call the county extension office and see what their suggestions are.

I'd be wary of adding sand unless you can add enough to help. If you add too little, you can make things worse.

How much of this clay fill are you bringing in and how much topsoil? What does the topsoil look like (it may not be much different from what your friend gave you)?

Is the soil currently below the level of the sidewalks and driveways? Because if it's not and you add soil, you'll be causing problems.

You should get a professional to grade the lawn before putting in the lawn. If you try to do it yourself, you can easily end up with lots of uneven spots.

Are you seeding or sodding? Seed costs a lot less, but sod is a lot easier to establish. If you seed in the spring, you'll need to be prepared to water more the first year to get it through the summer.

Thanks for your ideas. My husband thinks we can just spread the clay around a little, and I'm pushing for mixing some compost in first. Then we'll just add the topsoil/compost blend and hope for the best! I guess these things are always a little hit or miss. :)