After reading a few threads in this subforum, I decided to buy a Dahon Speed D7 2007 that was a lightly refurbished customer return. The bike is great for my commute in San Francisco--my only concern now is using it for more aspects of my transportation, like grocery shopping. I haven't had the courage to carry my bike into stores and restaurants, and anyway it's already heavy to carry out/into my apartment and definitely too heavy to tote around during shopping.

So my questions are: (1) should I get a bike lock for those times I cannot carry my bike with me or would you not recommend leaving a folding bike out under any circumstances, and (2) what kind of bike lock and what kind of rear carrying bag I can secure on to my bike rear stand would you recommend?

Actually, a rear carrying bag/basket would still be good for commute, so any suggestion about that would be appreciated too :)

I installed this on my D7 a year ago and it works well:

http://cgi.ebay.com/Bicycle-Black-Folding-Basket-Easy-to-Install-Bike-BSK13_W0QQitemZ380049588370QQihZ025QQcategoryZ420QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Very sturdy and seems built to last. I load it up often with heavy groceries and such