I think the LL (low level) part of CubeMX make up a reasonably thin abstaction layer for most project.
If "other people's code" includes libraries from the vendor, you can use the vendor-provided CMSIS headers for the MCU, and use direct register access code otherwise.
The datasheets/reference manuals for your MCU will be a required read.
> I use windows. What would be a straightforward way of getting to where I am programming/erasing/debugging in an IDE that is pretty simple to learn?
If you got along with MPLAB/MPLAB-X, you will have no problems with toolchains/IDEs available for Cortex M. Some are Eclipse-based, others not. The "industrial standards" like Keil and IAR are definitely up to the task, but lesser known work well, too. Many vendors push their silicon with a free or price-reduced toolchain based on GCC, and wrapped in Eclipse.
Even free one's are fine, usually only lacking in code density, optimization, and sophisticated debug features.
And nowhere in the ARM world does a toolchain add crap to the Hex file, just to get you paying for the commercial variant.
