Special Town Meeting voters on Monday approved additional funding to build a new Estabrook Elementary School, and a tax break designed to encourage Vistaprint Inc. to stay in Lexington and expand its local operation. The session also approved $1.5 million in road, sidewalk, and drainage improvements at Grove Street and Robinson Road in connection with the new Estabrook School. The expenditure was separate from the $2.6 million that members approved to cover increases in steel and other construction costs, which have pushed the price tag past the original $40 million estimate for the new school. The tax incentive finance agreement approved for Vistaprint would provide the company tax relief of more than $1.2 million over a 13-year period if it expands into a new building proposed for Hayden Avenue. The company is an online supplier of graphic design services and customized print products that is headquartered in Paris. But the company runs its United States operations out of Two Ledgemont Center at 95 Hayden Ave. Town Manager Carl Valente said Vistaprint’s expansion project could hasten the development of a 160,000-square-foot building proposed for Hayden Avenue. The new building is expected to generate about $600,000 a year in property taxes, Valente said, but without Vistaprint’s participation, it could take two additional years for the building to be constructed.