the first is ok, but the best order is我最近去看过她两次
the second我看得懂这本书or我把这本书看懂or这本书我看得懂
the third is ok, but better not with 去。it become:要上课了,你们快进教室吧。
nothing to say about the first one.
the second one, 把and得cannot be used in a same simple sentence
the third one, 进is more like the word enter,it‘s vt, but you put a去after that, it becomes a vi. better not be followed by an object directly right?