ra3 had much childish behaviour, nick faking, disconnect/join scripts, and shouts like "bridge, bridge, bridge".
there was a 1 year hype to play ra3 maps with cpma instead of ra3. via clanbase league. dont remember the year. after that league players went back to ra3.
start armor was different in eu/us. eu servers had more, cant remember the number.
at the end of q3 (2005/2006 or so) clanarena was the populatest mod, fast rounds.
Rocket Arena in Q1/Q2 was popular, but at that time most of the players played regular deathmatch (1v1/2v2/4v4/). I always had the feeling that the RA-mod (or CA nowadays) was considered like practise for the "real" Quake (to which I agree partly, even though I played a shit load of Rocket Arena). I think after like 2003 or 2004 people started playing more Rocket Arena than DM in pub games (in Q3) ... Those were the days!!!
In Q2 I would say ctf was the most popular mod. Ppl played RA2 for aimpractice and for fun. Tthere was an even more fun RA version in Q2 called Jailbreak. It was a mix of RA and freezetag, but instead of getting frozen on the spot when fragged you were moved to a jail cell where the most horrible monotone music was played. You had to stay there untill a team mate freed you or alternatively your team won/lost the game and it all started over :)