When I had the one m7 you could flash different radio versions

I was wondering if you could do the same for the m9. Currently I have a sim unlocked t-mobile m9 while using AT&T and I cannot get LTE to work properly. I was wondering if they were different radio versions I could try to see if an older or newer radio can fix this.

Does towelroot work for all versions of this phone?

Hey everyone.
I am using this phone for about a year now. When i originally got it in october of last year (HW version g900p.04), I was able to use towelroot with no issue. Since then I have installed a total of 1 OTA update, and immediately reran towelroot, which still worked.

I am currently at android 4.4.2, NE5.

I would love to just get a stock rom that still has root, but I haven't found much. I found an odin-flashable ROM of the latest OTA update, but it isn't rooted. Apparently you can install towelroot and that will root it for you.

Can I just install the latest OTA updates, and then use towelroot to reroot? Or would I need to odin flash recovery too?

Any help would be appreciated.

sm-g901f versions

I'm about to buy Samsung Galaxy S5 LTE-A SM-G901F Black.
are these versions of 901f the same: lte-a, plus, 4g+? i mean - same firmwares, kernels etc.