Is the transmission fixable or would it need replacing? Would it be better to sell the car?

I recently bought a 1998 Cadilac Eldorado. In the month I have had it I have had numerous issues start to occur with it, most of them minor, evap leak and a new speed sensor. My biggest issue is with the transmission, which has been leaking fluid slowly. About a week ago my reverse gear went out on the car. It will still reverse if the car is on an angle, but if it is flat the engine wont power it backwards. Drive seems to work fine, except for an occasional stutter around 50 mph and the fact that the car will not idle forward on its own with out giving it some gas. I don't have much money to get the car fixed, and am the only transportation for my dad who had a stroke and hear surgery recently. Is this issue something fixable, or am I looking at having to replace the entire transmission? Would it be better to try and sell it?