2 lbs is a lot of steeping grains.
I'd go 25% simple sugar (plain table sugar) and not use the candi sugar. 25% in 5 gallons of 1.100 is a little shy of 3 lbs. The sugar will help dry it out.
I'd just stick to light extract. You haven't really given us enough information to tell what style of beer you are brewing; a BGS, a BDS, or other. I'm assuming a BGS.
IBUs, you might push it to 50 IBUs. I just checked my notes and both my Chimay White and Duvel clone were around 35 IBUs for a 1.070 beer.
What yeast. Get one that attenuates well.