Manual shift gear

About your first question: I'm not sure. I think it's not going to engage at all, because I think reverse gear is not synchronized, so you'll need a lot of force to engage it. It will probably make you understand something isn't right...

About your second question: it's possible to shift without using the clutch, but it's tricky. Disengaging a gear without the clutch is not so difficult, but in order to engage the next one you'll have to match the revs exactly and it's not an easy thing to do, it takes practice in it's quite likely that before you're good at it, the gearbox will be damaged. It also has no advantage with today's cars, so I really can't recommend trying it.

You won't be able to shift into reverse while driving forward. you'll hear a strong squawk strong. It's possible to shift gear without the clutch exactly like it was said here before.

you will not be able to shift into reverse while driving forward...you will hear a grinding noise.....

yes its possible to shift gears without the clutch but on a sycronized transmission you are putting excessive wear on the syncros which are being worked hard trying to match the rpms..how ever on an unscyrnized transmission such as on a big rig truck you can shift gears without useing the clutch since theres no syncros to wear out...this will require the driver to match the rpms exactly.... many experienced truck drivers only use their clutch when coming to a complete stop and are so smooth at rev matching you dont hear any grind at all.

If you are going to put in into reverse while going forward, make sure no one is behind you.

 You can do partial clutch shifts....in cars.  Make sure you know what you are doing and don't do it on a new clutch or new transmission.  When you are at your shift point, pull it out with no clutch move shifter and then hit your clutch and put it into gear.  Its easier to do when shifting from 2 to 3 and 3 to 4.