Ok it said For each HQ choice in your army (not including other Techmarines, Servitors, Command Squads or Honor Guard) you may include a Techmarines.
Does this mean you can only ever have 1 Techmarine?
would this disallow me to take a Thunderfire Cannon?
How useful are Techmarines?
How useful are Servitors?
If I used Servitors with Heavy Bolters would they benefit from Imperial fist Chapter Tactics?