Scoobster,
From your own Post you were Downwind following another aircraft and instead of following them as you are required to do (conform to the pattern formed by other aircraft) you turned Base where you thought you should due to 'Landmarks' and effectively cut in front of them.
You do not know why they, in your opinion, extended their Downwind Leg - maybe they needed to increase the spacing between themselves and an aircraft in front of them?
They were aware of you and once you were established on Final they requested your intentions. This was perfectly reasonable (and we only have your opinion that this was said in an 'arsy' voice) - they probably wanted to know whether you intended to Land, in which case they would probably immediately have initiated a Go Around; or whether you intended a Touch & Go, in which case they could probably have continued with their Approach.
To the OP: You were on Base when someone said they intended joining for a Long Final - this means they were at least 4 miles out so (although you should obviously check) you should have had plenty of time to complete your Landing without interfering with them.
Emergencies excepted, I believe an aircraft on Final has priority over all other aircraft and that for Straight Ins this Rule trumps the need to conform to Circuit Traffic - not least because they are not intending to join the Circuit Pattern.
Good airmanship does dictate that at uncontrolled airfields good position reporting is required and it would be very poor to call "Final" at 4 miles.