Glad your kit arrived safely.

Be aware that Gretsch pickups are a bit narrower than standard humbuckers, so you'll probably need to get some adapter rings for them to fit in a standard humbucker rout without having gaps round the edges.

If you want to make the most of the quilt veneer, then I'd suggest staining it (at least the top), then using a clear coat over the top. If you want a solid colour, then I'd suggest paint.