If you were able to flash a custom recovery and it boots into it, then the bootloader was unlocked already; otherwise it'd just boot into the system or boot loop.
As for the adb, just check the L90 threads (unless I find mine before then) and wherever you unzip the adb.exe file folder to, open that folder in the explorer window, hold the shift key and choose "Open command prompt here". The adb commands will work then add long as you have the appropriate drivers installed.
---------- Post added at 03:47 AM ---------- Previous post was at 03:45 AM ----------
Oh... and yes. From your recovery you can now flash custom ROMs. Just make sure they are for that model and the instructions are followed.