I've been using Ds for ages, I've now introduced Us too (like a half moon shape DD). The curlier lashes are great for lifting downward facing lashes. I've made an illustration of the different curls I offer on my website here: http://www.lashes.ilovelash.com/pages/faqs.html

Its a common misconception that the EE curl should match the curl of the NL, I suppose because the closer the curl is matched the more surface contact for better adhesion. In my opinion what us Lash artists need to do is CREATE a shape that best suits their eyes and frames their face. For example a B curl on someone with naturally curly lashes may look similar to a C or D curl on someone with naturally straight lashes and equally a D curl on someone with downward facing lashes can resemble a B curl on someone with straight lashes.

So its all about accessing whats there and using the appropriate curl for crafting the look they're after.

With regards placement Madam lashes, you're right you have to be careful when lashes the uppermost row, I check in my dental mirror, if one is sitying proud of the rest I just remove that one altogether and leave it unlashed.

Hope that makes sense :)