Multiple examples of current limiting with TL494/TL594 suggest to use current sensing resistor between load(-) and GND. But I want load to be grounded. Can current sense resistor be placed above load(+)? Can I use external Rail-to-rail OpAmp this way to measure load current and then use it for TL494 feedback loop?
The configuration of the amplifier as shown in the question is not quite right, as differential amplifiers will yield better results. If the load doesn't mind a small voltage bump from the sense resistor, low side configurations are preferable. Either way, use one of these configurations:
Another option (that requires less resistors) is to use instrumentation amplifiers, check the common mode range.
Find the max voltage through the sense resistor and then calculate the gain of the differential amplifier.
Given the voltage drop in the other answer of the non-inverting differential amplifier high side goes above 10V this is not suitable.
Also looking at how R tolerance degrades CMRR and introduces DM gain error, you would need 0.1% R arrays like 10k hi and 2k low for $3 it is not a good choice.
Your circuit does not provide this CMRR of a differential balanced gain and also attenuates the signals to 1/3.
Therefore use a high side current sense IC of your choice,with 0 to 5V out with internal gain or whatever range of V to PWM Sensitivity you need.
Note that R8 does nothing.