SD card questions

[OnixIsThePewterGod]

I got a T4.1 for Christmas (yay! should have posted about it though) and I've been messing with the SD card slot. I want some guidance on how to write code with the SdFat library.

1. Which ways can I properly initialize the SD card for T4.1? Would overclocking (the microcontroller) make any difference? Right now I do it kind of like sd.begin(SdioConfig(FIFO_SDIO))
2. How would I get the maximum amount of speed (both reading and writing) out of my SD card (as it is)?
3. How could I perform raw reads/writes directly to the SD card (no files)? (mainly to gain extra SD card space)
4. How could I execute a program (binary format of course) stored on the SD card? (I know that unlike AVR, ARM probably allows for this)