Resizing or resampling

Help please with the above topic. I know there are endless topics on the subject but I just need a simple answer which I can't seem to find. Someone has given me a set of images to process and they are 10" x 6.662 with res 300. Ideally they should be 15 x 12 with res 300 . So here is my dilemma:

1. should I use the crop tool in photoshop and make sure resolution is set to 300

2. should I use the Image size and make sure Resample is checked and Bicubic smoother (best for enlargements) is set.

3. should I see if the client has larger images to start with (this will be the worst option as they have uploaded them via Dropbox which takes forever when there are 82 of them !)

Which method will produce the best result for printing purposes ?

First off, the images have the 2:3 (=4:6) ratio aspect and you want them to be 4:5, so they will have to be cropped. I imagine you will have to set the crop box for each image individually to be sure that important bits aren't being cut off. Second, after cropping, number 2 is the right procedure. As regards #3, the originals are 2000 x 3000 pixels, after upsizing they will be 3600 x 4500 - a 1.8X increase which shouldn't cause too much loss in quality if the original are sharp. On the other hand, there will be a slight loss (to a discerning eye). If the images have been previously downsized to 6 MP, the loss will be greater. Your call if getting a larger original is worth it.

Ask #3. If you have the option, it might be worth it.
Further: Agree with Elie.

82 Raw or jpg files shouldn't take "forever" to dropbox.

If you're using tif, you're doing it wrong