Is there anyway to change the stipulations of a living trust after the trustor has ped?

My grandmother is on the verge of ping away and has a living trust set up to where I can only live off the interest if I happen to need it; then when I die the money will be ped on to my kids. That is fine with me except for the fact that she says that when she dies I need to sell whatever I don't want asap (house, car, furnishings) or the government will take over 1/2 in taxes. I know this is not true as her estate is not worth 3.5 million, and am wondering if and how I will be able to sell her house and keep the money; as I have some debt I would like to pay off. If I cannot keep the money is it possible to give the house to someone or... is money allowed to be transferred directly from my account to pay off student loans, credit cards, etc??? Also, what happens when the trustee dies?? I am the only heir and need help understanding this whole process. Thanks!