hello folks , hope someone can help me

i have built some 433MHz CW transmitters and used them for tracking
model airplanes and stuff so I can find them if they get lost , the
only ones i have built so far are only a couple of mW output , the
company make they low power modules say no license is required for
their use

ok , so now i want to build a higher power one for greater distance ,
thinking of using the linx modules which can either have 10mW or 50mW
output at 433MHz CW

my questions

1) as power increases at some point i will need to get a technician
class license , no problem as i will do that , but my question is at
what power level is this required ? can you point me to where this
is defined ?

2) i know building little transmitters for sale as a product requires
an FCC registration number ... but building only a couple for your own
use does not .. correct ? ( if so hams couldn't ever build their own
transmitters )

thanks for any assistance ... stan