LT1242 Current mode control help

I am trying to implement current mode control in my buck converter using the LT1242 device. The reason I am using this rather than a buck regulator/synchronous buck device is because my input voltage is too high for the ratings typically. 

Anyway, I am having a few issues with the design. In the data sheet,, there are some examples of circuits using this device. I have changed slightly the flyback converter example slightly, I will attach a schematic to this post. 

My first questions is whether it is possible to implement both soft-start and slope compensation at the same time. My buck converter will spend most of the time above 50% duty cycle so therefore I will need slope compensation to ensure stability - but I would also like a soft start time to allow my output to reach the desired setpoint. It looks as though they are exclusive, because unfortunately the two functions use the same input pins on the chip - is there any other way I could implement both these functions within the same chip, or not?

Secondly, in the slope compensation where we use an NPN BJT that connects to the Isense pin through a resistor - how do we calculate this resistor value? There doesn't seem to be any equations for selecting the desired R.

When selecting RT/CT - is this purely a case of looking at the graphs and selecting both an RT and a CT that will give the right operating frequency? I wish to operate the LT1242 at around 500kHz, so have chosen 20kOhm and 100pF from the data sheet, but how do I know whether these values are optimized? 

I also have an issue with my Isense voltage sawtooth that is passed in to the current amplifier and compared with the error amp output. It is not symmetrical, and at times does not look what I expect. Maybe this is due to incorrect values of RT/CT or something, but I am sure someone more knowledgable than myself can input on this. 

The reason I have a buck converter and this chip is to regulate the DC bus voltage to a fixed frequency resonant half bridge converter. Therefore, the output voltage of the device is not fixed any will vary. How do I go about deciding on a maximum peak current etc in this case? I understand if we have a fixed output voltage our max peak switch current is fixed - however, if the output voltage varies, how can we choose a fixed value for max switch current for the regulator?

Finally, in all the designs the current sense must be taken from the switch node to ground. Is there a way to sense current through the buck output inductor instead, or elsewhere where the current sense voltage will not be referenced to GND?