I found that there are some people online that use regular nRFs as the receiver.
Is using the PA version with the antenna better for Rx or will the non-antenna version suffice?
I would assume it is the former because, although I don't have a 100% idea of how radio tech works, I guess the antenna would have a longer area to "scan" the air for signals.
And what if Tx was the regular version and the Rx was the PA version, would that work well? And vice versa?
The advantage of the high power version is increased range. The disadvantages are increased size, weight and electricity consumption.
If a pair of the low power versions with the PCB antenna will work at the range you require then there is no advantage using the high power version.
For the longest range you would need a high-power version at each end. For intermediate ranges it may be sufficient to use one high-power paired with one low-power device.
I presume all these questions relate to a single project you are working on and it would make a lot more sense just to stick with a single Thread so that we have all the information in one place.