I’d like to start with this one, convert SLC to GRD, I explained in the following posts,
Concerning your first demand,
Flood inundation is discussed in this thread,
In general I suggest to you read many articles and then start searching this forum, it has a lot of discussions, please use the help of SNAP, and google the process you wants to apply according to your goal and method, there area a plenty of videos and tutorial.