So I'm breeding to get just the right Roserade for me, but now I am wondering if there will be a difference in stats at Level 100 if I start with a Level 1 Roselia instead of going with a Level 1 Budew and evolve it.
Two Roserades with identical IVs and EVs will have the same stats, whether they evolved from a Budew or hatched as a Roselia. The advantage of breeding a baby pokemon is that baby pokemon can learn moves that their evolved forms cannot, and keep them when they evolve.
In this case, Budew can learn Water Sport, Worry Seed, and Uproar. If you want your Roserade to have any of these moves, breed a budew. If you don't need any of them, you can ignore the incense and just hatch Roselias.