Ok, the general problems I see with 7, 8 & 9 is that it will be practically impossible for anyone to elimiate any faction within the reign of one faction leader. RTR is designed to play slowly as it is, so we'd be essentially making rules that would make each player fail their goals. In addition, concentrating only on conquering the 'primary' target will create very strange and un-realistic borders. For instance, say one player takes on the Greeks, forcing him to expand into Ionia. This would bring Rome into conflict with the Selucids. If Selucia then became a major threat that had to be dealt with (primary enemy), we could find ourselves with an empire that stretched all the way to India, without ever having sent a single army north of the Alps. That just doesn't seem right.

Here's an idea though:
The Senate

We're playing in the Republic, right? No single man had total power during that time (ignoring Sulla, et. al.) so why should we? How about this... at the end of every player's turn, he/she must post a picture of the world (FOW on/off?) and a general description of the economy, military and enemy strengths/alliances. This can be VERY brief, it could be done in a few lines dashed out when the game is uploaded. The rest of us would then vote on objectives to be assigned to the next player. If the player achieves those objectives, they are 'successful' (forum equivalent of a triumph?) and if they do not, they have 'failed.'

The nice thing about this is that the requirements could be incredibly varied. It could be as simple as, "Conquer the Italian Peninsula." However it could also be something like, "Take provinces A, B, C & D. Build X building in city E. Obtain the maps of faction F. Build 2 fleets each with 2 decs, 4 tris, & 6 birs."

Now, this would require the non-players to check back in here regularly... so active commitment to the PBM would definitely be required. However, this would also provide some interesting interaction for the non-players as well.