OK, obligatory 'don't do it, it's against the law' warning, not only might it land you in hot water, it would possibly upset a lot of people who suddenly find their doorbells, garage doors, baby alarms, thermostats, remote control plug sockets etc. stop working or do weird things.
Now that's out of the way, you don't need the amplifiers to conduct your tests, in fact they may even be a hindrance as you need to implement TX/RX switching and walk a *long* way to make minor changes.
Better antennae make more range than adding extra power into a poor antenna, plus they scale for line of sight, so experimenting with extreme low power to achieve best range over shorter distances is useful before you jump into higher power.
There is a *lot* of information on antenna design out on the web, 434MHz is near as damn it a ham band so there will be lots of plans for 70CM antennae with gain, tuning one of those for use on your TX/RX pairs will make your life a lot simpler.
PIC code, if in C should be pretty simple to port to Arduino, I've done it a few times the other way round so PIC examples are useful if they work, even if you only read the code to see where yours is going wrong, having said that, 433MHz modules have been around a *long* time so there should be many Arduino examples out there, again choose one, test it, choose another, test it, see how the range works out (those AM modules are crap and range is easily affected by bad code, there are, again, plenty of web resources which explain it nicely)...