Ensure that you're warming up your rotator cuffs before doing any chest or shoulder work (look on YouTube), and do some warm up sets with very light weight for a few reps (3-5 reps). Stretch the body parts you're going to work after warming up on the cardio machine.
45 minutes to 1 hour is sufficient for weight lifting.
If you plateau which it sounds like you have, increase your calories by 500 (maintenance or above) for a week or longer (zig zag calories). Your metabolism has slowed down to achieve a homeostasis. You could be overtrained
as well which can cause this problem.
Also try different dieting strategies. Eat high carbs before you work out and immediately afterward to fuel your workout and recover properly, then for the rest of the day and night eat low carbs. Or eat low carbs for three days, and high carbs for days 4 and 5, then repeat. Moreover, clean up your diet more, try to eliminate processed foods, white bread, white rice, white pasta, and drink predominantly water.
Also be sure to switch up your routine every now and then. If you run, try riding a bike or elliptical. If you just run at the same pace for 8-10 minutes, try interval training. Also do different weight lifting exercises, integrate drop sets, supersets, pyramid sets, burn out sets, add more weight (progressive resistance), do circuit training or complexes
, and pair different body parts together.
Also remember to take a week off every now and then, about one week every 4-5 weeks you train to prevent overtraining.
You should also buy a skin caliper to measure your body fat percentage. Losing weight isn't necessarily a good thing, and not losing weight isn't a bad thing if it's muscle. Body fat percentage should go down, muscle should increase.
The basic theory is DO SOMETHING DIFFERENT. You body will adapt to forms of stress to establish a homeostasis. It takes doing something different to knock your body out of this homeostasis. Or you could just be overtrained, look for the signs and symptoms in the hyperlink. An undernourished overtrained tired body will halt your progress.