As an expert....I'm hoping the landscaper isn't just putting an inch or two of topsoil down! Really they should work it in with the existing soil or you may have a rooting problem and it will wash away. Also seed with a Rye and Fescue mix, the rye will give you a quick start 7-14days germination...
You can actually heavy prune lilacs unlike some plants. It will just come down to how much it has in reserves. Like you said if you want to worry about blooms right now then be lite on the pruning.
If you choose to prune heavy (which I recommend) then be prepared to not get any blooms for a...
How long do I need to let chicken poop (don't know if there is a better word) compost before using it in our garden? What does it do best around? Does anyone know the N-P-K of it? How long until I need to re-apply?
And the last question I swear...is it possible to sell this stuff? I have tons...