3bar, 4bar and z-link are all types of suspension chassis mounts. Like you said 4bar is the way to go simply due to the amount of bite you can get out of them. But then again you can buy a chassis with mounts for all three types of those suspensions.

A jbar on a modified acts as your "jacobs Ladder" on a sprint car.

A pull bar and a lift bar are both suspension components that mount to rear end and chassis which are used to increase forward bite. Depending on the chassis you go with will usaully determine what you run.

As far as swithing to a q.c. from a stock 9" you may be ok just all depends on the birdcages being used.

Best brands of chassis would be a Pierce, Rocket or a Diamond. Pierce would be a great starter car due to the avaialabilty of the cars (been around a while & cheap). Rockets and diamonds are newer cars on the RISE!

Tires will depend on the types of track you run. But a rf will last a month or two, lf all year, lr & rr 3-4 nights depending on tire comounds ran.

600hp motor would be good and competitive.