Reverse doesn't have a synchro - you should be at a complete stop before attempting to engage. I'm not sure about 2000 models, but 1st often doesn't have a synchro either.

 

there you go, thermistat just said reverse doesnt have synchro. so to all of you having problems in reverse only, then this means your reverse idler gear teeth are possibly worn out

 

All forward gears are synchronized. You're correct about reverse, it's impossible to engage until at a standstill.

No. It is totally normal for it not to engage reverse on the first attempt. It just depends, it's random. Selecting one of the forward gears and reattempting reverse is proper thing to do, it's normal and nothing to be concerned about.

If the car is sitting still (such as before you even start the engine) and you have trouble selecting forward gears, I mean even w/ a bit of force it won't go in, you would want to select another forward gear and reattempt your desired gear.
It's possible that it is an issue with motor mounts (on some models), shift linkage, worn/damaged gears in the transmission, or fluid related - such as seriously low fluid, maybe even running the wrong kind.
I was randomly locked out of forward gears (again, sitting still) in cool temps. when I tried Penz. Synchromesh fluid in my civic. Never had that problem with any of the many other trans. fluids I've tried.