Fishing chironomids requires a dead-slow retrieve which, if your tube is moving with the wind, would be almost impossible to imitate; which is probably why your success rate was low. Your tube was drifting with the wind faster than a real chronie moves and the fish weren't being fooled. When I fish chronies (which lately, has been every time I go out) I anchor my pontoon boat using a 10lb downrigger ball attached to 40' of braided nylon and it works like a charm.
For anchoring your tube, I would say a 5lb anchor would be enough. If you find you're not staying where you want, you could go up in anchor weight or just kick the tube gently to stay where you want. As for indicators, I personally don't use them but I know others on here that do (there's a couple of threads about this very topic so check them out). I think it all falls on personal preference. As for leaders...if I'm on the toon, I'll use my sinking line with a 6-8ft, 5x or 6x non-tapered leader. If I'm shore fishing, I'll bump it up to 10-12ft, 4x or 5x hand-tied tapered leader. It works for me so I keep doing it :thumbup: