While you have the answers, it's probably worth providing references, for when your opponent says 'huh?':
Ma55ter_fett wrote:1st question) At the start of a game can I deploy a 20 man crusader squad with a Chaplin attached, or would I have to deploy them separately and then have the Chaplin join the crusader squad?
Yes. This is answered in the
IC rules, in the second bullet point on page 48.
2nd question) can a Chaplin leading 3 cenobite servitors join another infantry unit? Say for example If I wanted the Chaplin with three cenobite servitors to join a 20 man crusader squad to make a 24 man squad.
Answered in the Cenobyte Servitor entry on page 27 of the
BT Codex.
2nd question) Can an entire BT terminator command squad be equipped with TH/SS or LC's?
Not listed as an option for them, so no.
3rd question) If the answer to the above is no, could I have a Chaplin attached to a terminator assault squad but hold that unit in reserve for a deep strike? Maybe justifing this to my oponite by saying that "The chaplin didn't start the game attached to the squad but in the battlebarge while waiting to be deployed he decided to join a unit of assault terminators"
Provided the Chaplain has some way of Deep Striking (Terminator Armour or a Jump Pack), yes. You declare if
IC's are joining units in Reserve and how they are going to arrive when you are placing them in Reserve before the start of the game. Explained in the 'Preparing Reserves' section on page 94 of the rulebook.
If the Chaplain doesn't have Terminator Armour or a Jump Pack, he can still be joined to the Terminators in Reserve, but they'll have to walk onto the board.
4th question) If the above answer is again "No" then can I deepstike a single model wearing terminator armor onto the battlefeild? Say if I were to deepstrike the chaplin and terminator assult squads seperately.
A single model unit is still a unit, and follows the Deep Strike unit in the same way as any other unit with the rule.
5th question) If a Chaplin in terminator armor with three servitors is attached to a terminator command squad can they deep strike with the servitors?
The Servitors have no access to the Deep Strike rule, so no. The unit will have to walk on.