Answer: Your zip code places you in zone 5A or the coldest part of zone 5. Gaillardia should be fully hardy in your zone -- it is extremely cold and heat tolerant -- but it does require a well drained, preferably sandy soil to overwinter successfully. A damp location or a heavy clay based soil could cause it to fail over the winter. Cutting it back in the fall would not cause it to survive or not. When you would see growth really depends on the weather and soil temperatures, but I would wait a few more weeks at least.
The grass may nor may not be hardy in your area depending on which cultivar you planted and your microclimate. (Microclimate can add or subtract up to about a half a zone.) However, assuming it is alive you should see new growth starting soon after the daffodils bloom. The new growth starts from the ground and comes up through the old stubble so it can be hard to see at first. Again, whether you cut it back in late fall or spring would not affect the hardiness.
Your local nursery staff can help you determine which plants should be hardy for you and where best to site them in your garden. Good luck with your plants!
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