Dex site says they released several add-ons (like special armor and such). Are they included in the GOG version and if not, are they going to be added?

They are in the GOG version and you just need to find them while playing( for the armors).

Thanks! Good to know.

Do you know if there are any usable melee weapons in the game? I never managed to loot any crowbars or chains, despite various punks using them.

The only weapons I used was pistols. Never bothered with uping melee so dont know if it gives you an option for some sort of melee weapon but you can still get augments that increase your melee dmg . And also I dont think you can loot most of enemy's weapons(including firearms)

Edit: Nope, nothing in melee skills gives you an option for melee weapons so I assume the games lacks the option to let you wield melee weapons.

I noticed that InvisySuit adds 4-punch combo ability, even though I didn't reach that level of melee yet (one level away). Is it an expect feature or it's a bug?