Is there any way to convert these points into any other points? as I have almost 4k honor points, but like 400 justice :L is there any way to convert honor to justice? or vise versa? or conquest to honor, or valor to honor? thanks.
none at the moment, and very doubtfull that they'll add one
No, I don't think you'll be able to convert one type of points to another. They're very distinct, and will remain the same as new patches come out.
Justice = Heroic and Old Raid content
Valor = Current Raid Content
Honor = Non-Rated PvP
Conquest = Rated PvP
If you were able to switch between them it would cause issues with people grinding PvP/PvE to get gear for the opposite which is -not- what they want. They might let you purchase PvP gear with Justice points at some point kinda of like you could do in Wrath though.
Also, once the new tier of gear becomes available, the old tier (currently purchased using Valor points) will be purchasable with Justice Points. At that time, they might choose to put arena/pvp gear from the previous season for sale with Justice points as well, but that has not been confirmed or even announced and is purely speculation based on how they did it in WotLK.
90 Orc Warrior - Ganglion | 90 Draenei Hunter - Fleshgrind