Hello, in order to do hydraulic modeling to delineate the floodplain for the events that you mention, you will need to first come up with the rainfall amounts for each of those return periods. You will then need to determine the amount of runoff generated from the precipitation event that makes it to the river system by using published empirical equations or a rainfall-runoff model, such as HEC-HMS, at locations along the river reach that correspond with cross sections in your hydraulic model. You can use HEC-GeoHMS within ArcMap to help in creating the HEC-HMS input files from your data.
The next step is to create the hydraulic model, such as HEC-RAS, by using the information that you mentioned - elevation, river shapefiles, aerial photos, landuse/land cover, etc. You can use HEC-GeoRAS within ArcMap to process your data and create HEC-RAS input files. Once the model has been developed, verified and run, you can also use HEC-GeoRAS to post-process the data and generate floodplains from the water surface elevations and your elevation data.
While there are other hydrologic and hydraulic models available, the HEC packages that you mention are very widely used and are free.
This is a very high level overview of what you will need to do and is not intended as an exhaustive list but, I hope it gives you an idea of what you need to do. Please don't hesitate to reply back with any specific questions. Thanks!
