I'm in Florida, and I would certainly say you received good advice regarding the loose mineral. I keep loose mineral year round, and a mineral block available, especially during the hot months. I would also advise that you have a conversation with your local County Extension agent as to what deficiencies the local soil might have. You will want to make sure the loose mineral contains those minerals. I would also send soil samples to your local university so you can have an idea what fertilizer makeup is needed.
The trick to handling cattle in Florida (as well as other hot/humid states) is to keep your cattle as calm/cool as possible. While I love working cattle with horses, I resist the urge when it is hot, and just carry a bag of feed into the pens and they come running... My cows are "bucket broke"...
Another tip is to know your sale barn. Not all are created equal, and I will say that I just caught a $400 error where the auctioneer said one of my steers was blind, which made the 500 lb steer sell for .75 per pound. After a quick call to let them know the steer got off my trailer with perfect vision, they pulled up the video of the calf's auction, and he stood perfectly calm and when the gate opened out to let him out, he simply walked through it as would any other calf. The sale barn's owner apologized and send an additional $400 to me. My mistake was not sitting for the sale, as this was the first time I had used this sale barn.
I'm in south central Florida, so another issue that will rob your cattle of weight is the presence of flies/mosquitos. Personally, I like to use rubs with the face flaps hanging down. I keep them damp with an oil based fly spray.
While the winters are mild, the grass typically quits growing in late October (depending on the variety of grass), so hay is still necessary. Know your hay growers, and I would suggest buying from them. If you let them load you in field, they typically reduce the charge per roll. I buy by the trailer load direct from the farm so I know the pasture my hay is coming from...
As far as top dressing your pasture with ryegrass, you would be well served by researching what variety of rye grass to plant. Personally, I am a fan of "Prine Ryegrass" as I have had great results, as long as we get some rainfall. I'm blessed to have one of the developers of Prine Ryegrass as one of my clients, and I follow his planting instructions to the T. In the past, I have roto-tilled the pastures I planted in Rye, though this year I am thinking of top dressing, as I just planted those pastures with Tifton 9 bahia and brown topped millet. The millet was just to provide shade from the sun to the young bahia sprouts as they came up.
The breed of cattle will also play a HUGE part in your success. You don't have to have ear'd cattle to be successful, but you'd better have cattle that have adapted well to this climate. I have Simmental that flourish here, but I have also culled fairly heavily because some really suck in this heat. Same with my Limo crossed commercial cows..
Good luck