[What cordless drill to choose from?]

Unless the Dewalt drill is an xrp 3 speed then it might be worth the hit going to nicad. I have used Ryobi lions for over 6 years., and my oldest battery finaly was showing some age. I moved up to the m18 line because I have been doing larger projects. In this day and age not going with a lion system seems like a bad idea to me atleast

[Impact drivers that you can disable impact function?]

Makita has a tool like that except the price is pretty insane at 500 bucks. You could get a whole power tool set for that kind of money

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=202072852&storeId=10051&langId=-1&catalogId=10053&ci_sku=202072852&ci_kw={keyword}&kwd={keyword}&cm_mmc=shopping-_-googleads-_-pla-_-202072852&ci_gpa=pla#.ULBMnYawV3c

[Why does dewalt not make an oscilating tool]

Yea it's really odd when corporate cousin porter cable has one.