You say you are considering leaving California but you don't say why. I'm guessing it is to get away from soaring prices, high taxes and repressive government regulations. Many people are fleeing California for those reasons.
I believe you will be most pleasantly surprised how much lower the cost of living is in Florida compared to California. Rather than try to answer all of your financial questions I suggest that you get them answered when actually on the ground here for your lifestyle visit or rental in a house for a month or so. Remember that you will find a lot more cash in your pocket simply because Florida has no state income tax.
Come in the summertime when rentals run around $1,000 a month, often with a golf cart and all utility costs included. The same house will rent for $3,000 in the winter months. If the house you rent does not include a golf cart then rent one for a couple of weeks. Zipping around The Villages in a golf cart is a major part of the "experience" of living here.
With regard to the heat and humidity remember the old show tune that "Only mad dogs and Englishmen go out in the noonday sun." Structure your daily activities so that you are indoors from noon to 5PM daily. Wherever you go will be air conditioned. All residences in TV are air conditioned and any that were built in the last several years have a SEER rating of 13. Cooling your house is not a major cost.
The Villages management is very aggressive on mosquito control. You will not find them a problem. The love bugs are a nuisance for a short time a couple of times a year but they do not bite. If you smash some with your car it is imperative that you wash them off promptly. Their bodies contain a juice that will quickly erode the finish on your car.
Making friends is easy here, even for an introverted person. Every week the local newspaper publishes a Recreation News supplement of about 50 pages listing clubs and activities for the coming week. I don't know that there is a group for F-100 or F-105 pilots, but I find it interesting that there is a group of WWII B-17 pilots that meets regularly.
I understand your concern about becoming disabled or needing assisted living. There is an assisted living facility here but it is extremely expensive. It is something that you could look into while you are here.
I am 75 and have become mobility limited due to a trip and fall back injury and subsequent back surgery but still can get around both in a car and a golf cart, using a four wheel walker when walking. I strive to stay active.
When you come for a visit please feel free to send me a Private Message through this web site and we can get together for lunch.
If you do decide to leave California I can think of no other place that offers the active living lifestyle and the extremely wide variety of activities that you will find in The Villages.