It is about a 15 minute walk from the zocalo. Friends have also recommended the La Posada Nueva. Has one of the better restaurants in Ajijic. Also on Lake Chapala. On my last trip out I took a taxi from Ajijic to the Guadalajara Airport for 140 Pesos plus tip.
Taxis are generally quite reasonable.
Auto rental at the Guadalajara airport is very expensive, probably twice what you would pay for the equivalent car in North America. There is a small car rental agency in Ajijic which offers fairly reasonable rates. I have stayed twice at the Hotel Real de Chapala on Lake Chapala. The rooms are quite large, including a sitting area. Hotel has a pool and nicely landscaped grounds.