My view of language learning is cognitivist, with strong connectionist influences. Such a view requires large amounts of input over time. The input should be balanced to avoid the need for massive restructuring late in learning. On the other hand, it is important that the training data not be overwhelming, and that there be feedback on errors, though the theory is equivocal on whether that feedback should be explicit or not is unclear. My personal feeling is that there are times when explicit correction is very useful.
Attention is required for learning to take place.
However, the attention need not be consciously directed at the form of the language. In general, I feel that students can benefit from having their attention drawn to simple, salient, and generally robust systems. On the other hand, the more complex relationships in language can overwhelm attempts to consciously learn them and may be best left to be acquired unconsciously. In my view, input is insufficient for developing fluent speaking skills. The brain needs to be trained not only to encode and recognize language, but to retrieve and apply it when called upon to do so.