We improve and validate TICP, our TCP-friendly reliable transport protocol to collect information from a large number of Internet entities. A collector machine sends probes to a set of information sources that reply by sending back their reports. TICP adapts the sending rate of probes in a way similar to TCP for the purpose of avoiding network congestion and keeps requesting reports until they are well received. In a first part of this work, we add to TICP a mechanism to cluster information sources in order to smooth the variation of network conditions during the collection session and to ensure an efficient handling of congestion at network bottlenecks. Simulations in ns-2 and PlanetLab experiments prove the outperformance of TICP over non adaptive solutions and the interest of the clustering mechanism in shortening the duration of the collection session and in decreasing the ratio of lost packets. In a second part, we adapt TICP to collect several packets of information from each data source. By the means of simulations, we compare the performance obtained by TICP to that obtained when using parallel short-lived TCP connections. Our main observation is that TICP yields shorter collection sessions due to its inherent multiplexing capability and that it avoids parallel Slow Start phases. Finally, in a last part, we study the impact of delegating collection to some proxy collectors. We explain our method for delegation and we show by simulations that for a judicious choice of proxy collectors, one can decrease considerably the collection session duration.