If you're still taking out loans, you can consolidate while still in school and not have any of the disadvantages. I did this back in September and consolidated every loan I had except my Perkins (I only had Direct loans and Perkings) and locked in those loans at a 5.1% fixed interest rate. If you're going to be in school for awhile, I'd wait until after July 1 this year though because I'm betting the interest rate will drop to around 3.5 to 4.0%.
You get a 6 month grace period on all direct loans and 9 month on Perkins. After the grace you can get a hardship deferal which you have to apply to every year. If you have enough debt, this hardship deferal will be no problem to qualify for (there's a couple of conditions you must meet to qualify). You can only do this for 3 years though. If you're in a longer residency, after these 3 years you can consolidate all your loans (I'll have 2 semesters worth of loans to consolidate) and get another 3 years of hardship deference. You can do this as long as you have some loan to consolidate, including perkins (although these are sweet loans so I wouldn't want to consolidate these). So you can get a total of 6 years and 6 months of deferment where the government still pays all the interest on the subsidized loans. I plan on paying all the interest on the unsubsidized loans while I'm in residency so that doesn't get added onto my already huge loan burden.
It's extremely depressing and complicated. Talk to your financial aid advisor about this.