FATHERS?!?! I had one, I am one. My son(17) gives me that "I do not believe it" look a lot. When it comes to thing with many keys,buttons & blinking lights he is right. IMO,All sweet peppers are green(unripe/ immature) until they ripen, then they are red(the only kind for many years)yellow,orange or purple. IMO, you are right, but I eat them all & they are great. By the way cucumber are eaten immature in my house( before they turn yellow).

I don't have a garden (but I will magically acquire one in about 1 month. Just bought a house with a raised garden). I know that several people on this forum has been pruning roots and plants and everything overwintering etc. I know some of them has taken plants out of the soil and potted them. Even removing all the soil from the plant (probably to minimize Aphid and other miscellaneous problems). But I would not be able to recommend any procedures. I suppose "carefully" would be my approach. I know that the local Wal-Mart sell soil moisture meters for about $5. Maybe getting one of those would at least confirm/deny possible wet roots as the problem (personally never tried one. But i will now that I'll probably do less container gardening). But, in any case, it does not really sound to me as a major problem. I am betting the yellowing will go away as soon as the plants dries a little. A few dropped leaves is in my opinion not something that will set the plants back for any significant time (with assumption of wet, but otherwise healthy soil and plants).

I hope you shaded it after transplanting. For the winter inside it lost it's hardness. 18 inches tall and wide doesn't sound too big. My peppers by the end of the season are usually at least 2' high, may be more, and at least 20 inches wide (more, if I let them be.) you can trim it a little, I guess. But not the branch that is producing. Support that branch, tie it somewhere, it can easy snap under wind. Other than that, nothing at least 2 weeks after transplanting, then you can start fertilizing...

I suggest you post on the vegetable forum and make your problem a bit clearer. It's hard to understand quite what the issue is. Photographs would be helpful too.