The problem is that Senators generally have less need for the party than the party has need for each Senator. With few exceptions, Congressman need the party more than the party needs them. Therefore, the balance of power is different in the party/member relationship in the House and the Senate.
Probably Frist could have done more, but I question whether he could have done all the things that you say.
Chairmanships go according to seniority based on what committees one is assigned to. However, one's initial assignment to committees is partly luck and partly clout (so Frist could influence). However, I think that, barring a vote from the caucus to change a Senator's committees (rarely or never done) or a change in committee membership numbers following an election, a Senator can stay on a given committee unless he wants to change. In other words, Frist cannot remove someone from a chairmanship, absent extraordinary circumstances and acting with the caucus' permission.
Base closing is under control of the base closing commission. Congress intentionally put that hot potato into the laps of former officials, former Congressman, former Senators, etc. Now each member of Congress and Senator can denounce the BRAC (Base Re-alignment and Closing) process and make efforts, almost always futile, to undo any decisions that hurt their Congessional District or State.
RNC efforts could certainly be influenced by Pres. Bush and Sen. Frist, but I think the more important contributions in the Senate races are provided by the National Repub. Senatorial Committee (NRSC). Since NRSC is now controlled by Senator Elizabeth Dole, it is doubtful that they would sanction those who break faith with the party.
As to the pork, didn't you know that Republicans don't do pork? But seriously, I guess Frist could block pork for those who mess up the party IF he ever learned how to block pork.
If Frist could get control of some of these Senators' tee-off times, maybe he could get more to tow the line. Controlling their golf access could be the solution. If only :)