The rules sit in Part 4 of the Companies Act 2014. Under section 157, the procedural provisions in sections 158 to 165 apply unless the constitution provides otherwise. Section 160 lets directors regulate their own meetings: questions are decided by a majority of votes, the chairperson has a second or casting vote on a tie, every director is entitled to reasonable notice, and the default quorum is two, or one where the company has a sole director.
Written resolutions come from section 161(1), which you can read in the text of section 161 on the Irish Statute Book. The resolution may consist of several copies in like form, each signed by one or more directors, and it takes effect when the last director signs (section 161(5)). Section 166 makes board minutes compulsory: the company must enter in books kept for the purpose every appointment of officers, the names of the directors present at each meeting and all resolutions and proceedings, as soon as may be afterwards. Minutes signed by the chairperson are evidence of the proceedings, and failing to keep them is a category 4 offence for the company and any officer in default.
Conflicts are handled by section 231. A director interested, directly or indirectly, in a contract with the company must declare the nature of that interest at a board meeting, and each declaration is copied into a dedicated book within 3 days. Filing deadlines then follow from the decisions: Form B2 within 14 days of a change of registered office (section 50(3)), Form B5 within 30 days of an allotment (section 70(7)), and Form B10 within 14 days of a new secretary (section 149(8)).