Rangefinder shooting...Leica IIIf?

Hi Everyone,
New to Leica forum...usually use Canon stuff 60D and G1X.

But, I want to try experimenting with film again, and using a nice rangefinder. Am looking at the Canon P rangefinder, or a Leica IIIf. Naturally being a Leica forum, you'd probably suggest the IIIf.

Is the IIIf tricky to use? Is the film loading, cutting the film leader, a pain? Does this camera have a nice bright viewfinder and accurate rangefinder focusing?

Any suggestions? Is the IIIf way to go? Parallax compensation?

If I got a more recent Leica with a bayonet mount can I still use the Leica thread lenses (LTM) ...suggestions much appreciated.

Thank you,
cheers Dave S