Microsoft Word is not an image processing engine; sure, it has some nice features, but, in all, it is used just to display, arrange, and lightly modify images. Your choices are, from what I can see:
- Batch Resize: Use a utility to batch resize the images you want, prior to inserting them into Word.
I can't really think of another method, personally; if you want the pictures all the same size, it is best to process them FIRST, and then insert them second.
Would recommend you take a quick look at IrfanView, nice easy to use free utility that can do the batch re-sizing for you; you then can just insert into word via the converted files, and not have to worry about the sizes.