I have about 34x flow in my 90g tank. I do not have any pumps pointing directly at the corals. If anything, I would like a little more flow in my tank.
As far as ssb's, I used to have one in my tank, with much less flow than now and I still had problems with the pumps blowing the sand around.
If you plan on adding a substrate, you might want to consider a little heavier type that won't blow around so easily. As far as maintaining the ssb, I would suggest that you vacuum it often otherwise it will become a nutrient sink again. From my own experience, I just didn't have to time or energy to try and keep an SSB clean and I ended up going bare bottom two years ago and have not looked back.