Loft is the thickness of the batting. Battings come in very thin ( low loft) to very high lofts and everything in between. The batting packaging tells you the loft of your batting. Such as (loft= 3/8").
As for your question, sure you can ( pad) areas, with layers of batting to make those areas puffy after quilting.
Things to keep in mind-- when you cut the pieces make sure they are big enough to be caught in the stitching ( if you just spray baste them & stitch around the shape without actually stitching the batting down it will shift/ ball up when laundered. ) also use a batting that does not require dense quilting-- warm & natural allows up to 10" between stitching lines- might be a good choice, some battings need to be quilted every 2" - if you used one of those you would also need to stitch inside your (shapes) if they are larger than 2". There are some nice high loft polyester battings used in tied quilts & comforters that allow a good distance between lines & are very puffy (1"-2"). They could also be a choice.