Hi Jo,
I always use the water soluable on top of any design,it helps lay the stitches on top of the fabric a bit more.there are many different weights of that as well,the one I use is the one at ATG .So far it is the best I have used,it is fairly economical,and it has never failed me yet.
By using the WSS on top of the fabric ,it has been my experience that no matter how dense the stitches are ,the wss seems to smooth them out and make them lay beautifully. I never use the spray adhesive as it gums up my needle and can sometimes make a big mess .I just use the sticky back.
When ever you re-size a design,you should add and remove stitches from it. By making it smaller than the original design ,it would then make it much more dense,and harder to get it to come out nice.By removing some of the stitches,you then take some of the away so it sew out nice.
I also sew a lot of different animals,I always use Wss on the top.Animals do tend to have very dense stitching,so they look more real.So the birds feather's look like feather's and the pet hair looks soft and cuddly as most kitties and puppies are........awwwww. Any way, by using the wss on top of the fabric it helps the stitching to lay really nice. Try it on something quick and simple and easy to sew.Try just sewing just the bird on something the same weight fabric that you are trying to use. Use the Wss on the top.Please give it a try,you will never sew another thing without it.
I cannot stress enough about doing a test sew out.this helps to decide what materials you will need for the finished item.I know it is time consuming,but it is better than ruining the item itself.It will save you from either having to tear out the stitching,which will take you longer than the 60 minutes,or tossing the item aside to become an ufo.(unfinished object). The best part is you then have something wonderful to use for something else like a quilt,or sew it onto a bag with ribbon.There are many things you can do with them,trust me they are not a waste of time.The benefit is now you have a list of materials you need to sew the item intended.
I try to look at the design itself to judge the density of it,Good designs,most all of the animals,flowers ,leaves usually have more density to them.I just got in the habit of using the WSS as all my things looked so much better with it. I guess I really don't think too much about the density of the design as by using the WSS on top,it just always comes out really well.
I hope all this has helped and of course it is only one opinion,I am sure other's out there will add some to this forum as well. Pat has great idea's and of course ,Ann always has a great answer to things.Maybe one of them can answer your question about the stitch guidelines you asked about. Have a blast,and Happy Stitching!!
If I can answer anything else for you let me know........I am always happy to give it a shot! I like to help put when I can...........
Toodles!