Working with 1440 x1080 footage?

I'm going to be working with some footage shot at 1440 x1080 (interlaced I believe) with an AVCHD camera. I will have other footage shot at 1920 x 1080 that needs to be edited with it.

1. Anyone know why a camera would be designed to shoot footage at 1440 x 1080 instead of 1920 x 1080?

2. Is it better quality wise to let the footage scale up to 1920 x 1080 or should it just be downconverted to work in a 1280 x 720 sequence?

Thanks.