We will be in Florence in early April and have booked a VRBO not too far from Piazza Mercato. It's difficult to get a sense of distances from the I-net maps. As a reference, what's the distance from the area we will be staying in to Santa Croce ? Grazie e' cordiali saluti.
One thing to know about Florence is that is very walkable! Even if it is a 30-minute leisurely walk from one place to another - there is so much to see and admire that you will not even notice the time.
From Piazza Mercato (close to Mercato San Lorenzo) to Santa Croce is about 20 minutes - and that is a comfortable stroll with a few stops to check out a building or two along the way.
In a pinch, I use google maps frequently to figure out the closet public transport. Which I have always found to be pretty reliable and good for a long haul from one place to another (even in the rain!)
There are bike rentals throughout the city, but to be honest with so much to see and so many people on the roads, I find bikes to be a bit tricky.