Here's an older thread that should help you with info about Mary Queen of the Universe Shrine and the Catholic church in Celebration, as well as info on cab companies:
I can answer only a small portion of your question. Rather than paying for a taxi to and from a supermarket, get a grocery delivery instead ... the $12 or $20 delivery fee will be much less than the round-trip taxi fare, plus you won't need to take away precious time from your vacation to get to and from a store, navigate the aisles trying to find items in a store where you don't know where anything is, etc.
Our taxi ride from the Fantasia miniature golf course to our offsite hotel at 5399 Irlo Bronson Highway (about 5-7 miles) was $21 including tip. We watched the meter go up about 85 cents just sitting at a red light on Disney property.
Our car had broken down which was the only reason for the taxi. The next day, we rented a compact car (Kia Rio) from Enterprise for $30/day. And they even came to our hotel to pick us up. You might consider that option instead. You can PM me for details.
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