Can I fit restricted hinges in place of a standard hinge?

Yes you can provided that the track width is 18mm wide and the length of hinge is available.
Please note that side hung window hinges have one restrictor on the bottom hinge and top hung windows have restricted hinges on each side of the window. The latter is important for safety reasons should someone fall against the window (please be aware that some websites sell only one restricted hinge per pair on a top hung window and this is an extremely dangerous practice with a top hung window).

What is the maximum gap that is restricted?

The size of the window can vary the gap by a small amount but it is intended to open to around 100mm.

Are restrictor hinges handed?

The top hung hinges aren't handed as they have a restrictor on both sides so it is just a case of fitting the correct one to the correct side. The side hung hinges are handed as only the bottom hinge is restricted for safety reasons. In this case, when viewing the window from inside, if the handle is on the left side of the window frame it is a left handed hinge. See the diagram here:

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Handing diagram

How to determine the handing of a restricted upvc window hinge.

Does the restrictor re-engage when the window is closed?

Yes it will re-engage when the window is pulled past its restricted point and also when closed it will return to its set position.