The inclusive e⁺p single and double differential cross sections for neutral and charged current processes are measured with the Hi detector at HERA. The data were taken in 1999 and 2000 at a centre- of-mass energy of √s 319 GeV and correspond to an integrated luminosity of 65.2 pb^-1. The cross sections are measured in the range of four-momentum transfer squared Q² between 100 and 30000 GeV² and Bjorken x between 0.0013 and 0.65. The neutral current analysis for the new e⁺p data and the earlier e^-p data taken in 1998 and 1999 is extended to small energies of the scattered electron and therefore to higher values of inelasticity y, allowing a determination of the longitudinal structure function FL at high Q² (110-700GeV²). A new measurement of the structure function xF₃ is obtained using the new e+p and previously published e+p neutral current cross section data at high Q². These data together with Hi low Q² precision data are further used to perform new next-to-leading order QCD analyses in the framework of the Standard Model to extract flavour separated parton distributions in the proton. [ABSTRACT FROM AUTHOR]