The register shall record all the facts reported to him under N.H. Rev. Stat. § 80:22, N.H. Rev. Stat. § 80:27 and N.H. Rev. Stat. § 80:33 and any other facts required to be reported by the tax collectors of his county in a book or books to be kept for that purpose. He shall keep an index thereof showing the location of the property and the names of the owners to whom taxed, the names of delinquents, the purchasers at tax sales, and of those who pay delinquent taxes or redeem from sales. The index may be the same as that for other records in his office or a separate one, as each register shall determine. All documents received by the register from the tax collector shall be returned to the tax collector within 30 days.