DOG QUESTION...TRAINING!!!?

I have a 3yr old labrador/retriever mix. Last year we moved from Idaho Where my dog had 3 1/4 acres to run and do what he liked on. I spent about 5-6 hours a doy playing and taking care of him a day. Now he is staying about 1mile away from me at my aunt's house in california. He has an extreamly small yard compared to what he's used to and has to be kept in a small dog run area in her back yard because he fights with y other dog and her dog also. This has been a huge change for all of us and has taken a huge toll on my dog. Since we have been down here I don't get to spend a lot of time with him because I have lots of homework to catch up on because I was out of school for a year and was sick. I DO see and talk to him everyday and play with him while I am there with him, but the closer that It's been to my senior year the n=more busy I have been getting. I only get to walk him maybe about 2 times a week. All of this change has made him angry towards other dogs, jelious, and he dosen't obey commands well. I know this is caused by the change, but we can't take him anywhere or to the park when there are other pets because he fights with them. I need to know what kind of toys, training divices,..ect that will help me controll him on walks, he constatly pulls until about 7 blocks down so about 10 min of walking time. Spending more time with him is going to be a big hel but I just can't do it untill we have our own house where he can be in our backyard instead of a mile down the road. This way I can talk and play with him while eating lunch and doing homework. For now I need so major help and advice on what to do because my aunt either wants me to spend more time with him or find him a new home. I can't see how I can do my homework and spend time with him t the same time, but would like to keep him! I need so very temparary distractions that will help him calm down and not become depressed. Thank you for your help!!!!