What is the mechanism of azulene synthesis? In the Organic Syntheses preparation of azulene (http://www.orgsyn.org/demo.aspx?prep=CV7P0015) there are two reactions. First is a clevage of the C-N bond in pyridine and the second one is the annelation of a seven-memebered ring:



I suppose that the first step of the first reaction  is a nucleophilic substitution by pyridine at the 1-chloro-2,4-dinitrobenzene, but I have no idea how the mechanism could continue. Could some one please help me? Thank you. 

Also, for the 2nd reaction, is it an electrophilic substitution at the cyclopentadieneyl anion, or does it have an  entirely different mechanism?
The @orthocresol link to the Zincke reaction is a good start to the mechanism. You are correct about the first step. Dimethylamine adds to the electrophilic pyridinium salt 1 as illustrated in 1 --> 5.  The reaction is driven by loss of the poor nucleophile (decent leaving group), DNP-NH2. The (Z)-isomer 5 is in equilibrium with the (E)-isomer 6 but the reactions leading to azulene 12 require a cisoid conformation to allow for cyclization.
Cyclopentadienide anion, which is delocalized but for convenience is shown as a localized anion, displaces dimethylamine which is protonated by the methanol in the reaction mixture (see your link to Organic Synthesis). Fulvene 8 must generate the geometry shown to complete the remaining steps to azulene (9 --> 12). ADDENDUM: An added thought. The transformation of 8 ---> 10 may be a 4n+2 disrotatory thermal electrocyclization that forms the new sigma bond of 10 with cis hydrogens.