I wanted to know more info about special classes and now to share it with you. Thanks Brent for answering. You may already know this but it was new to me.

1. Q:How customizable are heroes? Can I change his weapons, armor and appearance?
A:At launch, heroes will have less customization than other classes, although it hasn't been determined exactly what that means yet. In particular, the characters available in the founder store will be mostly static. That said, they'll take on the appropriate chapter/clan/legion/craftworld and gender of the character that spawned them (if it makes sense), and we'll be looking into adding more customization in the future.
2. Q:How many heroes are you plan to add to the game?2 founders and 2 non founders? Michael Chan told me that some sub factions will have unique heroes, Will every sub faction will have unique heroes or not?
A: At the moment we have 2 earned in-game, 2 for founders as you said. For some sub-factions we have to tweak the heroes to fit the lore, but we're not planning on doing that for all of them.
3. Q:How will they be different from regular class will they have just higher stats or also special abilities?
A: Heroes (like the Master of Relics) are powerful by themselves, but they're more useful as force multipliers on the people around them. They're kind of like super-support classes, so it doesn't make sense to just spawn a bunch of them at once since they can't boost each other. Heroes are there to lead everyone else.

Elites, on the other hand (like the Damned Legionnaire) are more like Terminators. They serve a role, but they're powerful fighters in their own right so you need to pay to spawn them. The distinction should be up on the store shortly.

only 2 in game and 2 for founders?
so i suppose for space marine is terminator librarian + lotd and master of the relic?
no chaplain?

how a librarian and a master of the relic can be sidegrade?
how a lotd and a terminator can be sidegrades?

LOTD and Termies are Elites, so id assume the ingame Heroes will be the Librarian and Chaplain.
The Founders hero is only the Master of Relics atm, so it means theres still one Founders hero to come out (or more if they actually dont hold to this 2 founders heroes).

I hope they arent content with only 4 heroes per faction though, that doesent sound like much variation tbh (plus two of them being Founders specific).

well i hope is like that 4 "hero" is only and only "hero-hero" (i past we recived some confused info before the RT description update).
but that means i need to buyy another 25$ dollars hero T_T

I also hope it`s hero- hero. For orks big mac mek and weirdboy. But as I understand it`s two heroes and to elites. I`ll ask Brent.
There will be special heroes like priest for SW and dark apostle for WB

i have a sneaking suspicion the Damned Legionnaire is the founders store side-grade to the deathwatch marine. although it could be something more mundane like the normal veteran or sternguard veteran.

the devs dident sound so hopeful when the subject of librarians making it into the game for launch has come up before. so i suspect that the master of relics is the founders store side-grade to a standard captain or commander and that the second in game hero for space marines is going to be the chaplain.

that leaves the question of what would be a good founders store side-grade to the chaplain would be. perhaps the Master of the Rites, Reclusiarch or Master of Sanctity

Interesting, so what im trying to understand is that heroes are powerful units, but benefit more from supporting the entire squad/army more. What is their power level compared to elites? I'd assume a tier higher. But that's good so it's stops hero spamming. But that brings me to another dilemma.

Now with elites being powerful units in themselves, what's to stop people from just spawning a bunch of elites forming a squad led by a hero? Won't that be a bit unstoppable unless another opposite force does the same thing.

spawning elites and heroes costs RP and so long as they don't go overboard in giving elites and heroes extra Armour and health player skill and organization should be the dominant factor. but i don't think there is any way to stop an organized group of elites and heroes spanking the zerg into oblivion, it would take an organized and well geared group to take them on properly.

Maybe there won`t be psyker classes, atleast not at launch. Who knows. Playing as Chaplain or Big mek is also cool.

There will indeed be psyker classes, the Chaos roster even features a psyker as a basic unit.
And the Librarians were mentioned dozens of times by Brent and how they will not be as accessible to the SM as they will for Chaos (psykers, not Librarians...)