I attach front, sides and back with ST30 and use a little iglue at the very front part of the hairline. I never go more than a week w/o doing a re-attachment but I could easily get 2-3 weeks hold with st30. As for the top being thicker that the sides, its not going to blend correctly and "lay" into your existing hair if its too thick. You just need to start off with a density and you can adjust from there whether you start at 65 or 70%.