Molecular Orbital Hybridization vs Delocalization for positive charge stabilization
Basicity is the ability to donate a pair of electrons.
In the case of pyridine, the lone pair is in a sp2 orbital. This orbital does not participate in any resonance, and is smaller than the sp3. This means the electrons will be closer to the nucleus due to stronger attraction, making the pyridine a weaker base, since it's harder for it to donate these electrons.

Tertiary carbocations are more stable, that is correct, but you should look closely on what that means. A tertiary carbon is carbon atom that is to 3 other alkyl groups , not just any other atom. Alkyl groups are weak electron-donating groups, therefore stabilizing the carbocation, because they increase the electron density in the electron-poor center.
That is why according to Markovnikov's rule, the electrophile, in this case the proton, will bond to the less substituted carbon - in order to create a more stable secondary carbocation, which the nucelophile (the chloride) will attack.