Winter Cycling - cool weather clothing

I have only been cycling in warm weather in bike shorts. What are options for cooler weather? Are their bike "longs" with padding in them or do folks where workout long pants over bike shorts? Also, i have been wearing a long-sleeve technical tee under my bike jersey.

The long sleeve tee under your jersey is a great idea (as long as it's made of some kind of polypro or spandex, NO COTTON). For pants, you can get a pair of knee warmers that cover a lot of your lower leg (if you have short legs like me), or full unpadded tights over your bibs, or padded full length bibs. They all exist and have different uses. For me, I wear just short bibs when it's warm, short bibs w/knee warmers when it's cool, and wind-proof tights over short bibs when it's really cold. Anything colder, I would throw my vented snowpants over my bibs.

Up top, your layer is a good idea next to your skin. Over the jersey, you can throw on a fleece when it isn't windy, or a wind vest over the top of that when it is. Alternatively, you can wear a windproof jacket instead of the fleece and vest.

For your legs, you can go with tights, leg warmers, and knee warmers ... and if it gets really cold, tights over shorts, with sweatpants and maybe even splash pants over top.

Some ideas to get you started:
http://www.nashbar.com/bikes/SubCategory_10053_10052_200484_-1_200275_200339
http://www.mec.ca/Products/product_listing.jsp?FOLDER%3C%3Efolder_id=2534374302692571&bmUID=1254537750367
http://www.mec.ca/Products/product_listing.jsp?FOLDER%3C%3Efolder_id=2534374302885011&bmUID=1254537830275

if you buy a cold weather (long sleeve) jersey, should you get it so an undergarment still fits nicely under it without causing the jersey to do a boa constrictor on you? or does the spandex allow for adjustable snugness whether or not a thin undergarment layer is used?

Any long sleeved jersey should accommodate a base layer. If a jersey fits so tight you cannot, you likely have the wrong size. I'm referring to regular knit fabrics, not form fitting lycra based ones.

While lycra is fine for shorts ..... I never use it in tops. It doesn't allow for the best movement of moisture. My favorite base layer for cold weather is Craft Pro shirts. They are a rib knit, so they fit close to the body, and move moisture like crazy. Defeet Un D Shirts for more moderate coolness ..... like the 60's.

I stay away from slick textured fabrics as they just don't move moisture or feel as warm next to the skin. For the life of me I can't see the appeal of Under Armor brand for instance......

Mt all time fav for cool weather is a Pearl Izumi Kodiak light short sleeve jersey and Defeet armskins. Super versatility.

When it gets really chilly look for tights and jackets that have windstop on the front but none on the back, thus allowing your sweat to move through and out. I use that strategy till about 0F, when I add another windproof shell over everything. After 30 min in cold temps (like down to -20F) my wife and I brush the frost off each others backs.