The signups for the beta have been officially opened as of today, and if you haven't signed up yet, make sure you do so on Quake Champions website. Along with sign ups, there has been a plethora of new information on the game available.

Champions
There hasn't been much information released about the champions, just their names. Here are the playable champions that await from beta start in no particular order: Nyx, Scalebearer, Anarki, Clutch, Galena, Ranger, Visor and Sorlag with more to follow.

What is known from previous trailers are some of the abilities and other specifics. Nyx's active ability ghostwalk and passive ability wall jump, Scalebearer with his charge ability, Ranger with teleportation orb (and potentially a melee attack), Visor with "wallhack" Anarki with his passive ability, air control and Clutch with his shield ability.

Another QC specific seems to be that Champions drop armor shards upon death, DOOM glory kill style.

Weapons
The weapons available in the beta so far are Heavy Machinegun, Super Nailgun, Super Shotgun, Rocket Launcher, Lightning Gun and Railgun. There's probably more weapons to come (e.g. Plasma Gun and BFG), but nothing official yet. Compared to Quake Live, the weapon stats do not differ that much and should be more or less what's everyone used to so far.

The innovation comes in the form of weapon classes. While not much has been said, there will a weaker class of starting weapons opposed to what you can pick up. You can't start with any weapon available on the map and you can't start with Heavy Machinegun, Super Shotgun, Super Nailgun, Rocket Launcher, Lightning Gun or Railgun.

Arenas
The arenas in the beta so far are Blood Covenant and Ruins of Sarnath. Blood Covenant is a remake of an old classic, Campgrounds and as it seems it's destined to be one of more popular maps in this iteration of Quake as well. Keep in mind that it's not a carbon copy of the old Campgrounds and that there are major changes done to the map. Bridge to rail is still there by the looks of it, pillars and mega pit as well. The biggest difference seems to be in addition of an outdoor segment, a sort of courtyard. Rest of it should be familiar to anyone that has ever played a Quake game.

Regarding pickups, there's a total of 15 health items on the map. The items are most likely mega health and minor health bubbles (5, 25, 50). There's 3 armor pickups available on the map. There's still no information on how will the armors tier. There also seems to be either Mega Health (DM) or Heavy Armor (Sacrifice) spawning, depending on which game mode is played. Another QC specific thing are Cooldown items. Those pickups are represented on the map in the form of an hourglass and will reduce the remaining time you need to wait to use the character's ability again. Fourteen of those are on Blood Covenant and are scattered throughout the map. One final note about this map, the power-up spawns on pillars top level. Which power-up, it doesn't say, but I guess it will be Quad Damage instead of Protection (possibly a battle suit renamed).

Ruins of Sarnath is a completely new map to Quake whose design reminds a bit of Unreal Tournament. The map features outdoor as well as indoor areas. There's 13 health items, one of which is Mega that spawns in the same room (Eye of Cthalha) as either Quad Damage or Protection power-up. In my opinion, the pentagram probably stands for Protection power-up since it was the same in Quake World. Other items include 3 armors and 14 cooldown items. Only thing that I can say for sure is that it will be interesting to see Quakers playing a completely new map after half a decade.

Both maps include obelisks which are there for the Sacrifice game mode and both of the maps can be played in standard deathmatch mode.

Modes
The Quake website shows only two game modes announced so far, one of which is the classic death match. There shouldn't be any surprises with this one, nothing suggests major changes to the mode and it will probably be the same old stuff everyone played for last 2 decades.

What's actually new is Sacrifice. Not much has been said or seen about it (even if you count the leaked QuakeCon videos). There's obelisks on both maps that serve as control points which in turn amplify your frag count depending on how many of them you control. To simplify it, imagine Domination mode from UT. You control obelisks as you'd control the points, the only difference is that you don't get points for controlling the obelisks. The reward is making your frags count more. The frag multiplier depends on how many obelisks your team controls at the time of making the frags.

Sources: Official site, Champions, Weapons, Arenas