This thesis discusses the measurement of the Higgs boson production cross-sections in the H→WW*→ eυμυ decay channel and the Effective Field Theory (EFT) interpretations of combined Higgs boson measurements. The results are obtained using 36 fb^-1 proton-proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV, and recorded by the ATLAS detector in 2015 and 2016. The measured H→WW* cross-sections are defined within the Simplified Template Cross Sections (STXS) framework, where the gluon-gluon fusion (ggF) and vector boson fusion production modes are studied. In the case of the ggF production mode the cross-sections are measured as a function of transverse momentum and number of jets. With the H→WW* measurements high transverse momentum can be accessed, which is sensitive to new physics. Seven cross-section measurements with the STXS framework are perfomed using the H→WW* decay. This thesis also presents the first ATLAS EFT interpretation of combined Higgs boson data in H→γγ and H→ΖΖ* →4l channels. Finally, the EFT interpretation is also performed including measurements from the H→γγ, H→ΖΖ* → 4l, and H→WW* channels. The constraints are obtained on the EFT parameters sensitive to modifications of the Higgs boson couplings to strong and electroweak gauge bosons, and to the top quark.