Hi Patricia -- welcome to the forum and congratulations on your new Outback!
As for clothing, the most important IMO are hat, sunscreen, sun glasses and a bottle of water. Depending on the weather, you might bring a windbreaker and a waterproof plastic bag to stow it in if it gets too warm. Your life vest also makes a great windbreaker. I prefer shorts since my legs don't mind the cold and I don't like anything over my knees when pedaling. Just dress comfortably.
Footwear is important. I like aqua shoes since I launch and recover from the shore. An old pair of tennis shoes will do also. In colder weather there are a variety of boots, booties and etc. A forum search will also give lots of information.
As long as you have your Drive and paddle, there isn't anything else you need to get you back in case of problems. Both should be tethered to the boat (along with your fishing rods) so you can't lose them no matter what.
Extra safety equipment depends on whether you are alone, how far out you go, water temperature, etc. Again, there are extensive lists that have been posted on the forum. If you're close to shore in decent weather, I think a PFD is sufficient. This really depends on your comfort level though. There are some who wouldn't go out the door without a VHF, EPIRB, flares, reflective tape, flag, bilge pump and flight plan (and i'm not knocking it). Sudden weather changes account for most of the unexpected events that can get us in trouble -- if it starts to look suspicious, don't mess around.
Many folks like to add positive flotation in the form of pool noodles just in case. I always carry some extra light line in case I need to tow (or be towed) or tie up somewhere. This can double as an anchor or stake-out line for fishing. You should practice capsizing in a safe place -- this will boost your skills and confidence. There are a couple of instructional u-tube videos if you need some tips.
Pedaling technique you'll develop naturally as you get experience. With paddling, it seems like there is a stroke and style for every day of the year. I'm no expert at all, but if you pedal upwind and paddle downwind it's hard to go wrong! You might want gloves if you're going to spend any time at it. A little experimentation will pay off.
You definitely need a solid reliable rooftop system for transportation. There are some great deals on ebay, Craigs List, Penny Saver or newspaper classified for used rooftop systems. I've bought all my rooftop systems this way. Thule and Yakima make good systems, although I prefer the rectangular Thule bars to the Yakima round bars where the saddles tend to twist out of position. Make sure you know your car's requirements before you buy used -- you can call the companies directly for assistance. There are also several lift assist systems available, several of which have been reviewed on the forum.
Finally, novices sometimes have trouble dealing with sizable boat wakes. You can't go wrong by taking them head on until you get comfortable with the mannerisms of your boat. Have fun!
