You have to be guided by real use cases and experience, which probably means experiment in the absence of comprehensive data..
SAW -> LNA should provide the best strong signal performance (out of band signals won't overload the LNA and mix with each other into in-band signals).
LNA -> Saw should provide the best weak signal performance (weak signals are amplified before the loss and noise figure of the SAW. But look at its 3rd order intercept point (3IP) : a measure of its linearity to strong signals - can you overload it?
If the GPS receiver is nearly as sensitive - and linear in the presence of strong signals (same 3IP) - as the LNA, then the simplest circuit with fewest noise sources may also be the best performer. (And if the GPS overloads easily, an LNA ahead of it without selectivity will only worsen the situation)
So without more information, no single answer...
The dimensions look about right to me, assuming your circuit board has an e_r on the order of 4? It's always best to simulate if possible though!!!
You obviously can't get +1dBi in every direction, but you can probably get that radially from the dipole (17.9 mm x 2 mm) part anywhere but back towards the PCB.
Best Answer
These nrf24 modules use the 2.4 GHz ISM band. The wavelength of such a signal is around 12 cm. Antennas get useful when longer than one quarter of that so in this case 3 cm. That is in the order of the length of that meander. You adding wires to it actually makes the antenna perform worse !
At 2.5 GHz you cannot do much with standard wires. You could disconnect the meander on the module (there is probably a resistor or capacitor feeding the signal to the antenna) and use an antenna for Wifi instead. Note that these will have a small coax cable to feed the signal to the antenna. These are quite small and hard to solder properly. Some experience is required ! Then mount that Wifi antenna somewhere where it has some space around it.
It is hard to predict what range you will get when mounting the module between other modules. Anything containing electrically conductive structures will harm the effectiveness of the antenna. It is always a good idea to give the antenna some space to "breathe".