First of all, best of luck with everything! 

I just had RNY gastric bypass on 9/12/11.  I have had LADA (latent autoimmune diabetes in adults - also known as Type 1.5) for 25 years with HBA1C's always in the mid to high 7's.  Because of the type of diabetes I have, my endocrinologist has said that I would still need insulin after surgery.  And I do.  But here's what's different - prior to surgery, I was on 3 injectables (Lantus, Byetta and Novolog) and on actos, glimepiride and metformin, as well as bp and cholesterol meds.   As of now, I am taking Lantus and Novolog ONLY - everything else is gone.  And my blood pressure is normal and fine - and last labs were good.  I have not had an HBA1C drawn yet, but I know from my meter readings that my next one will be significantly better. 

Because you are eating so little in the weeks following surgery, you likely will go off many of the drugs you are on.  I had normal blood sugars for 2 days after surgery, but as soon as I began to drink some water, I started going up.  We played with some insulin doses in the hospital but significantly less than what I used to do.

Now that I am almost 3 weeks out, I am back on Lantus and mealtime Novolog, but in very small doses with MUCH, much better results.  My blood sugar stays in a normal range most of the time, and I'm taking so much less insulin and no pills at this point.  My endo and I have agreed that I will likely go back on some metformin once I can take pills (which should be soon).

It's all a bit of a moving target for a while for me because every 10-14 days my diet changes to accommodate a bit more solid food.  But, my weight is going down.  So, I expect adjustments to be frequent.  I test myself about 5 times a day anyway, so I am able to make those adjustments by testing and monitoring myself.  That has been key.

Your question about dealing with lows is an excellent one and it was one of the things that I hounded EVERYONE about prior to surgery - for months.  I have had 2 lows since the surgery and both of them have been in the morning.   I have been able to address them with about a tablespoon of juice mixed with a little water.  First, liquid goes into your blood stream so much more quickly after surgery because of the changes to your digestive track.  So, you don't need as much or to wait as long for the effects.  Secondly, mixing juice with a little water cuts the carb count, which will keep you from any dumping, as long as you keep the portion size down.  And, depending on the surgery you are having, you won't have the capacity for much anyway.  (And you aren't hungry.)

Sorry for the long post, but these were the kinds of questions I had prior to surgery and, like you, what my doctor said just didn't seem conceivable to me.  But, he was right.  Many, many Type 2 diabetics do go off all of their medications while in the hospital.  I hope you are one of them.