Welcome to a great way to get in shape and stay in shape.
Let your body tell you how much to do and at what rate you can step it up. If you are concerned by your health history, it wouldn't hurt to check with your doctor. As long as you are cleared to exercise, then go for it. My only word of caution would be not to overdo it. We all overdo it at times. Doing too much too quickly will actually set you back. You wake up sore the day after a long ride, so you decide not to ride that day. The next day you're still sore, so again, no riding. And so it goes. or worse, you injure yourself grounding yourself for weeks at a time. Best to build it up slowly.
The rawness question has been well covered. Go to a bike shop and check your bike for fit. Fit is the single most important factor to successful cycling. The bike's gotta fit or you're gonna give it up. Get some decent cycling shorts and wear them commando style, that is, without underwear.
To find some riding buddies try these links:
www.bikeflorida.org
www.floridabicycle.org
www.coastalcruisers.org
www.caloosariders.org
Southwest Florida has some very active clubs.
Hope this info helps you enjoy this sport.