Wow! I didn't expect such a great response. Let me try to answer the questions:
1) All my kits have been ales, mostly from Midwest but a couple from Williams. Summer ale, Pumpkin, Holiday, Irish Red, etc. No home recipes at this point.As long as your volumes are correct going into the fermenter your gravity should be almost spot on as prescribed by the kit. This leaves fermentation as the variable.
2) I always get the Wyeast smack packs with my kits. They are fresh and refrigerated until use. They always swell fully so I assume no yeast problems.Wyeast has about 100billion cells per pack, dry such as Safale has 200 billion. OG over 1.05 or so will require a starter or multiple packs when using liquid yeast, dry yeast can hand more gravity. Don't forget that no 100% of the yeast cells will be viable in a pack.
3) I take an OG and 2 or 3 SG to determine when my fermentation is done. Guess I didn't realize I could use an ABV calculator like SterlingHopper was kind enough to include in his post.How long do you leave your beer in primary and at what temp? I typically let it go 3 weeks, its definately finished and clear at that point. I keep my initial temps just below 65 for the first week and then let it go up to 67-68 for the remainder. Those are fermenter temps not ambient.
4) I do keep detailed brew day notes on each batch, including the final chilled temp of the wort. I don't get the temp of the fermented wort, however. Should I take that as well when I am doing an SG reading?
Thanks for all the input.