Doing squats with a weight belt can make a big difference in how much weight you can put up. Belts can also help support you during other heavy lifts such as the deadlift and the clean. You don't have to spend a ton of money, but a good belt should be a gym-bag staple.
To do deficit deadlifts, stand weight plates. They don't have to be very high—one inch will do just fine to start. As you get better and feel more comfortable, you can increase the height, but don't stand on anything over three inches tall, especially if you have a hard time maintaining a neutral spine.
If you're unable to do pull-ups, do them with bands, or do negatives. If you can't get 10-20 reps, do 5-10.