- For dumbbells I use HealthLife(green weights) and MaXX Fitness(grey weights). My dad bought them some donkey years ago so I don't know how much they cost. But they function fine for me. A pair of good training gloves are vital though -- dumbbells have a coarse grip and can hurt when lifting heavy weights.

- How heavy a beginner can lift varies with each person. Try a weight and see if u can perform 12 repetitions(reps) of an exercise with it. If the last few reps are difficult enough to make you want to stop, that's the weight you should start out with.

- Personally, I don't use barbells. Maybe it's the scare that if I perform barbell exercises now I will stunt however little growth I still have in me(I'll be 20 this year). However, pretty much all barbell exercises can be substituted with a form of dumbbell exercise(and you save costs on buying a barbell and plates for it too!).

- Get a bench that can be adjusted into an incline, flat, or decline position. If possible, get one with a leg curl extension also.

- I don't use exercise balls(not really necessary I think)

To lose weight, cardiovascular exercises(jogging, swimming, cycling) and diet are the keys. Weight training will aid you by building muscle which ups your metabolism(muscle burns calories by themselves also). To train your abs, crunches(a form of sit up, but you don't raise your upper body so much) can help.

To know more on exercises and weight training, refer here.

Glad to know that you're taking the initiative to make yourself healthier.

Actually, I think it's the other way round. Jogging is harder on the knees compared to the bike.