Winstrol has many positive effects. It will certainly give an increase in athletic performance and strength not just overall strength, but improvements in power, speed and agility. Winstrol will also increase red blood cells although not as much as other steroids and it increases nitrogen retention in the muscles which helps speed up recovery. In addition it will enhance protein synthesis and lowers SHBG (Sex hormone-binding globulin) which is the product in your body that limits the overall effectiveness of steroids. This is why Winstrol is a popular steroid to add to stacks as it can improve the effectiveness of the other steroids. On the cutting side of things Winstrol is excellent at preserving muscle while on a calorie deficient diet, greatly enhances vascularity as well as promotes a dryer and harder physique.
During the two 'off' weeks, an ECA stack can be used as required. ECA will not cause such a pronounced down regulation and desensitization of the receptors, certainly not to the extent of clen. Ephedrine has a short half life in contrast to clen which results in times throughout the day where the betas will partially recover from stimulation by adrenaline and nor-adrenaline. Potency is also much weaker that that of clen, as it is not a specific agonist. Ephedrine is also thought to increase the conversion of endogenous/exogenous T4 to T3 through the activation of deiodinase enzymes responsible for this process. This is important as clen is known to slow the rate of T4 to T3 conversion. As a side note, some bodybuilders will use T3 concurrently with the Clenbuterol/ECA cutting cycle (together with certain anabolic/androgenic steroids no doubt!) in an attempt to at least maintain plasma T3 levels.
More specifically, the methylcobalamin form of B12 is recommended, as it has been shown to be the most effective. Taking B12 gives you a huge boost of energy while training, and more importantly, greatly helps your recovery.