Hello Angel! The best thing for a newcomer to do is to jump in and talk about what you like best about this topic. :D

For example, Ivarr makes an interesting point. What were, if any, the contacts and relationship between Celts and Germanics? The problem indeed is whether there were still well-defined Celtic groups in Continental Europe by the III-IV century. Politically not, probably (I might have a serious memory lapse here), but maybe certain zones kept Celtic tradition somewhat alive. I like to think that the Alps were one of such zones, judging from all the local legends that show both Celtic and Germanic origin. (There's a valley in Italy where they still speak a form of Gaelic.) There might have been some sort of contact between old Celtic families and Germanic newcomers, some cultural exchange.