[Sony Xperia T, TL, TX, V] LaZiODROID:
Detail is always good - much better than a "i rooted my phone and now it doesn't work" post. I agree, information is in many different places - very easy for that to happen.

Yes - that is, if your bootloader was Locked when you started this whole adventure.

- Maybe but maybe not!,

No - the bootloader unlock is a whole process in itself. DoomLord's (fantastic) root kit will root your phone - meaning, it will root your phone's current system, to allow read/write access to the system's files. When you unlock the bootloader, that allows you to write to partitions (kernel aka boot, radio/baseband? etc.)

Since right now, what you need to be able to do is flash a stock FTF (to get your phone working again), make sure your phone is disconnected from the PC. Drivers --- all you should need is Sony PC Companion installed (which installs base drivers for the phone), and Flashtool (http://xdaforums.com/showthread.php?t=1943886). After you install Flashtool, you will need to go into its folder - inside of there is a "drivers" folder. go in there and run the EXE. On the left side, make sure to click/check the driver for your phone (xperia T or TL or LT30p or whatever), plus the Fastboot driver, plus the Flashmode driver. Let it do the install. **NOTE** i dont know if Win7 has "driver signature enforcement" - if you notice the drivers are failing to install, that could be why. Look into how to temporarily disable driver signature enforcement and try these 3 drivers again. You will need them!!

Stop here for a second - For the purpose of flashing an FTF (i.e. getting your phone back to working state), do not connect the phone yet.

When using Flashmode, don't connect the phone at all - Choose flashmode, then choose the FTF, then wait for it to process the files, then it will pop up to tell you when to connect the phone. And this is very important - make sure the phone is fully OFF, then, hold the VOLDOWN button, then plug the usb cable in - when you see Flashmode start moving along, you can let go of the VOLDOWN button... and put the phone down gently .. you dont want to distrub this delicate process :D.

This may all depend on your bootloader - if your bootloader is locked, you likely cannot get the phone into Fastboot mode.

Right - flashing via fastboot may not be possible right now if your bootloader is locked.

Yes - let's skip the kernels for now - and get you flashing a fresh FTF so you can start over. I suggest that once the FTF is flashed, and the phone can boot normally, you dial the Service Menu number and look to see if your phone has "Bootloader Unlock Allowed: Yes" or "Bootloader Unlock Allowed: No". -If it says NO, it means NO! There is currently (as of Feb3/2014) no way to get around this. This means your bootloader cannot be unlocked, which means no custom kernels, and no fastboot! Custom ROMS can still be flashed - just those that are Locked Bootloader-friendly (meaning, the custom rom operates just fine/is based on the Stock kernel - whatever version is preferred will be mentioned in the dev's first post of the thread). There are a few.. like XperimenT and T-Hybrid. I like those.

I'm going to be safe and assume yours says No (like mine, because everyone should suffer with me!! :D) You can then ROOT the system like you did, then install CWM Recovery for locked bootloaders (v8!! dont use v9 for now), then you can flash a rom or do whatever. If the custom rom you're installing is based on a stock kernel whose version number is different from your phone's base, then you may be able to find kernel zips that are flashable via CWM - since they are stock kernels, the flash will be allowed because they are signed or whatever. Example: Since you're going for LT30p .141 FTF, you're on the 141 kernel. If the rom you're installing says it recommends the .145 kernel, find the LT30P .145 kernel zip. You can flash that right after flashing the ROM. I think that the 141/145 kernels are similar to each other so in this case, you may not even have to flash from 141 to 145. But you will - because you will become addicted to flashing like the rest of us and you will want to observe/compare how the ROM behaves on each. :D

I think what it's really asking you is to Unlock Your Bootloader. Unlocking the bootloader is kind of considered a global root (because it allows writing to any partition on the phone.

Yes - hopefully above we have tackled that.

Agreed!! Good luck!