Well as someone who has good stamina you could potentially use that to your advantage and have one long cardio session a week - working up to 2 or 2.5 hours. You'd want to perhaps alternate between the bike and the treadmill in say 20 min lots. That could help burn some fat and teach your body to metabilise fat a little more efficiently.

There's no point in thinking about that if you don't want to spend that much time in one session and get bored easily though. You'd also need to keep up your weights to prevent you just getting smaller rather than leaner which can happen.

Sounds like you enjoy resistancw work which you could keep up but just work out a structure which would suit you time wise. General principles which you already know would be not to work the same muscle group 2 days in a row so you could either do your whole body in a weights session and skip a day or two or break your body up into muscle groups to do a shorter session more often.

Cardio wise I think it'd be good to get into the habit of doing some say at least 3 probably 4 times a week but that could include your soccer game and unless you decide you enjoy it enough to go down the endurance path wouldn't need to take more than 30 mins.

If you want to do sprints - say to improve your explosive ability for soccer you'd want say at least a 15 minute easy warm up before doing intense intervals. Depending on the max speed of your treadmill you might be able to do some short sprints on that and I guess your exercise bike too if the resistance isn't set too high.

I wouldn't recommend mroe than 2 sprint sessions a week and since you probably sprint a lot playing soccer one is maybe more realistic - just make it a good one.

You'd already know Scrap's threads are good for stretches.

You can work the bags in a similar way. You might have short, hard rounds on your bag to really get your heart rate up with timed rests.

You will find that with pushups and boxing etc you use and strenthen your chest muscles a lot. To counterbalance that you will need to put some emphasis on your back when you do weights. It will also help to keep you from developing a hunched posture which will make your stomach look fattier than it really is.

Chin ups are great for your back plus some light dumbell exercises - on hands and knees, dumbell in one hand and raise laterally and return in a controlled fashion to feel the muscles right in the middle of your back. Light weight is best otherwise you use the wrong muscles which won't really help your posture.

You might want to check out the bodyweight exercises thread that Hitmanddony put up - there are heaps of good exercises in there.

I'd also do a search on plyometrics because they'd be great for your soccer to I imagine. You just need to make sure you have a safe surface for plyometrics and skipping. Doing those exercises on normal floors WILL damage you. You'll get shin splints and potentially back problems - i knew a guy who had to stop boxing for a while because he fractured his back this way! It sucked for him because he'd just won a national junior title and was doing really well!

If you don't have sprung floorboards you might be able to pick up some rubber matting made for this purpose somewhere.